Ok so, not going to lie, I like D&D a lot, but I kind of hate Armor Class.

I don't mind the system of "roll your bonuses against a target number to hit". It's certainly more efficient than systems that require opposing rolls or success levels. I don't even mind armor being rolled into your defense (as opposed to providing damage soak).  What grinds my gears is that outside of a few specific class features (usually restricted to monks), in most versions of D&D your armor class is almost completely locked in at character creation. You can get better armor (though it's usually only a one or two point difference), and in rare cases you might improve your dexterity modifier by one, but there's no inherent AC improvement through leveling up (even for fighters). I find it to be a bit immersion-breaking that a character can spend years of their life getting into swordfights, and not get any better at not being stabbed.

Thinking about this lately, I realized that it's probably the reason why hit points work the way they do in D&D. Gygax always insisted that HP partly existed to represent the characters' ability to avoid debilitating damage, which is why it increases with level when pure physical resilience probably wouldn't increase at that rate, and I suspect it developed that way because the AC system couldn't do it. My point is that the AC system makes a certain amount of HP bloat almost necessary.

This is borne out by looking at other games, whether it's Dragon Warriors, WFRP, Cyberpunk, or even Call of Cthulhu. In games where HP increases are rare or even impossible, it is almost always because defense is some kind skill or stat which you can improve with experience.

It's weird to me that more OSR and OGL games haven't tried to address this. The only one I know of is Radiance, which makes avoiding attacks another function of the save system.

Having a to-hit roll and hit point damage allows you to create a Cartesian plane.  In the NE quadrant are threats that can hit you and deal a lot of damage; in the SE quadrant are threats that can hit you but only deal minor damage; in the NW quadrant are threats that are unlikely to hit you but deal a lot of damage when they do, and in the SW quadrant are 'mooks' that can't really hurt, and even if they do, it's insignificant. 

There are other ways to create differing types of threats, but if you only have one axis, it's harder to differentiate them to create those four types of threats. 

In 1st and 2nd edition, I felt that my AC always improved. 

In the game that I play with my friends, we have a Base Defense Bonus that increases as you gain levels.  While your AC doesn't get better very quickly, it is true that opponents that could hit you at low levels might miss you more often.  If you want higher level characters to have less to fear from lower level opposition, providing some bonus to AC to reflect that might make sense. 

From a 'satisfaction' stand-point, I think that players should expect to hit 'equal opposition' more than 50% of the time (I ballpark it at 75%).  Hitting on a 6+ (instead of an 11+) makes a difference in how combat plays. 

Yes it does, but maybe not the extent that you might think.  After all, early D&D wasn't this bloated, and for most levels barely felt bloated at all to many people.  Of course, where the line crosses into bloat is going to vary by personal preference, too.

There are several factors to consider, with each person having their own view of the pros and cons of trading off between the factors:

- How far do you want to push ease of handling?  This includes the simplicity of avoiding armor as damage reduction versus whatever complexity your alternative brings, as well as tracking various states on each combatant.

- How many creatures in a fight?  The more creatures you have, the more compromises you have to make here, despite what you think on the other factors.  (Doesn't mean that you make the same compromises that I would make or start in the same place or set the creature threshold in the same place--but where ever you start, you are going to have to change past N number of creatures in the fight.)

- Where do you draw the line on bloat?  I draw it on triple digit hit points, except in the rarest of cases (e.g. super tough dwarf fighter at maximum level, immense dragons, etc.)  I'll force the math to cap it there, even if it costs me elsewhere.  Others will work out the math of the system to suit, then let the hit points fall where that dictates.

- How much do you want low-powered creatures to threaten high-powered creatures, and how much?  If you want it possible for any character to die at any time (e.g. crossbow bolt to the head), then a D&D-style system is a poor fit, though you might be OK with certain versions at low levels.  If you want superheros running around until exhausted, everything short of bloat is a feature, not a bug.  It's in the middle, where a lot of people live, that the margins matter.

How you deal with all of that isn't changing one thing in a vacuum.  For example, I want less hit point bloat, AC getting better over time (moderately at first, then slowly), more deadly than any WotC version but slightly less deadly than early D&D low-levels, more risky than early D&D high-levels, weapons doing more damage than most D&D versions, and more variety in critical hits.  Executed, that's going to produce something not exactly D&D, but still capable of using Armor as AC, increasing hit points, and at least mitigate most of your points.  It can't eliminate them entirely, because that's the nature of the trade offs.  Getting there is being clear about the goals of the system and then making the widgets and math do that. 

For example, I let Armor and Ability mods to AC stack (like early D&D) but put some caps on magic boosts (but not entirely), and built the game around an implied setting where the better armor is hard to get and not everyone can learn to use it productively (more so than most D&D versions).  Ability scores can improve slowly.  Net result is that in the low levels, characters can find mundane armor to upgrade in most cases, with later magic and ability score improvements chipping in later.  Between incremental AC improvements and slowly increasing hit points, later characters are more resilient, because the two have a multiplying effect.  Slightly more hit points and slightly better armor class can be quite notable in combination.  Then to keep the risk, I went with a Wound Point/Hit Point variant, and carefully considered what went directly into my equivalent of Wound Points, building it directly into the system and math from the beginning instead of trying to glue it onto an existing D&D version. 

So there is room for nuance.  The trick is there is only so far you can push an existing system when it made trades you don't like, before you are essentially rewriting the system from the ground up.  Rooting out hit point bloat in place that you don't like is akin to pulling crab grass in a yard instead of spraying it or digging it all up and starting over. 

Greetings!

Cap Character Classes at 50 Hit Points. Remember to reduce Monster Hit Points by 50%.

Semper Fidelis,

SHARK

The AC system fundamentally has nothing to do with hit point bloat. The AC system goes back to 1974 OD&D and one could argue that through Chainmail and other gaming traces back even earlier. There was no bloat back in 1974. It's all about the way the rules have evolved.

(1) Hit dice have changed. Supplement II Greyhawk in 1976 had magic-users using d4's but now they have d6's. Fighters have gone from d6 to d8 do d10. Making the types of HD larger means HP totals will become larger.

(2) The transition from rolling to averaged numbers. In the old days if you rolled a d6 sometimes you'd get a 1, sometimes you rolled a 6. The 5E way is to allow for each d6 to become an automatic 4 hit points. That can cause HP bloat.

(3) CON bonuses are greater now. Boxed set OD&D had a +1 HP bonus for each level if you had a CON of 15 or higher. 5E allows for a +1 if you have a CON of 12, +2 for a 14, +3 for a 16, and so on. Larger CON bonuses cause HP bloat.

(4) Higher levels cause HP bloat. A lot of OD&D games in the 70's tended to cap out at level 10 or so. AD&D lifted that to level 20. Those extra levels mean more hit dice and more CON bonuses, so philosophy has contributed to HP bloat.

So really all you need to do is look at the way the rules have evolved from edition to edition. Over time the norm has been an emphasis on "player friendly" rules, which almost always means more hit points. I've been pondering running a 5E campaign where every character gets half hit points but damage stays the same. 

The armor system I liked was from Earthdawn (Savage World sort of uses its dice system, complete with exploding dice).  You armor was just Damage Resistance, but the critical hits in that game (extraordinary hit) would defeat your armor.

That could be brought over to DND easy enough. 
Using Ascending AC Your AC would be equal to your Dexterity score. 
Level bonuses to AC for non-martials (+1 @ 3rd/+2 @ 6th/+3 at 9th/+4 at 12th) and every odd levels for semi and martial classes (+1 @ 1st /+2 @ 3rd/+3 @ 5th/+4 at 7th/+5 at 9th/+6 13th)
Shields add to both AC and DR, Buckler could be 1/1, Shield 2/2 and tower shields 3/3 but vs arrows would be 6/3
Armor's DR could be Leather 2 / Chain 5 / Plate 7 / Full plate 9.
Protection Rings would add to DR, Saves and AC.  Bracers of Defense could act like shields bolstering both AC and DR since they don't work with Armor.  Bracers grant an AC [11 + 1d4] but for this system it would grant 2 - 5 AC & DR (Using the AC normal Bracers of Defense grants and subtract 10)

Using OSE rules (b/x) a 1st level fighter with a 16 Strength(+2) & Dex (+1) wearing Plate Mail (3) and using a Shield (+1) would have an AC of 19
@5th level they have acquired +1 Plate and shield so now have an AC of 21 (19 without shield)
@9th level they have acquired +2 Plate and shield, AC is now 23 (20 without shield)
@14th level they have acquired +3 plate and shield, AC is now 25 (21 without shield)

Using the modified rules above our 1st level fighter would have
a base AC of 18(16 without shield) (Dex 15 +2 for shield +1 for level) DR of 9 (7 without shield).
@5th level 15 (Dex) (+3 for level) acquires +1 plate (8 DR) and +1 shield (3/3)
AC of 21 AC (18 without shield) DR of 11(8 without shield)

@ 9th level 15(dex) (+5 for level) acquires +2 Plate(9DR) and +2 shield (4/4) and a +1 protection Ring
AC of 25 (21 without shield)  DR of 14 (10 without shield)

@14th level 15(dex)(+6 for level) acquires +3 plate(10 DR) and +3 shield (5/5) and a +1 protection Ring
AC of 27 (22 without shield)  DR of 16 (11 without shield)

Using OSE rules (b/x) a 1st level Magic user with a 16 Dex (+2) wearing robes would have an AC of 12
@5th level they have acquired +1 protection ring and Braces of Defense (12) would have an AC of 15
@9th level they still have their +1 protection ring but found better Bracers of Defense(14) and acquired a Cloak of Defense +1, would now have an AC of 18.
@14th level they still have their +1 protection ring but found better Bracers of Defense(15) and acquired a Cloak of Defense +2, would now have an AC of 20.

Using the Modify rules MU with 16 dex
@1st level MU, AC of 16, 0 DR
@5th level MU, (+1 level) AC of 20, 2 DR
@9th level MU, (+3 level) AC of 25, 4 DR
@14th level MU, (+4 level) AC of 28, 5 DR

Using OSE rules (b/x) a 1st level thief with an 16 Dex (+2) wearing Leather (12) would have an AC of 14
@5th level they have acquired +1 Leather and +1 protection ring so now have an AC of 16
@9th level they have acquired +2 Leather and +1 Prot Ring & +1 cloak of defense, AC is now 18
@14th level they have acquired Bracers of Defense (+5) and +1 Prot Ring & +3 cloak of defense, AC is now 21

Using the Modify rules Thief with 16 dex
@1st level Thief, (+1 level) AC of 17, 2 DR
@5th level Thief, (+3 level) AC of 20, 4 DR
@9th level Thief, (+5 level) AC of 23, 5 DR
@14th level Thief, (+6 level) AC of 31, 6 DR

14th level fighter AC of 27 (22 without shield)  DR of 16 (11 without shield)
vs 14th magic user AC of 28, 5 DR
ve 14th level Thief, (+6 level) AC of 28, 6 DR

The Thief would have the highest AC then the MU and finally the fighter but the first two would get hit a lot harder due to lack of DR.

For monsters, just base their DR around their AC.  For non-ascending AC, it would be DR 10 - their AC.   For Ascending AC their DR would be equal to their AC -10.  Then adjust it by monster type.  If they have scales add +2, if its dragon scales add 5.


1HD bandit with a 13 AC would have a 3 DR
6HD Basilisk with a 15 AC would have a 5-7 DR
10 HD Red Dragon with a 20 AC would have a 10-15 DR

From there just let Natural 20's simply be armor defeating hits.

So was this something you had in mind?

Quote from: finarvyn on August 12, 2022, 11:15:28 AM
The AC system fundamentally has nothing to do with hit point bloat. The AC system goes back to 1974 OD&D and one could argue that through Chainmail and other gaming traces back even earlier. There was no bloat back in 1974. It's all about the way the rules have evolved.

(1) Hit dice have changed. Supplement II Greyhawk in 1976 had magic-users using d4's but now they have d6's. Fighters have gone from d6 to d8 do d10. Making the types of HD larger means HP totals will become larger.

(2) The transition from rolling to averaged numbers. In the old days if you rolled a d6 sometimes you'd get a 1, sometimes you rolled a 6. The 5E way is to allow for each d6 to become an automatic 4 hit points. That can cause HP bloat.

(3) CON bonuses are greater now. Boxed set OD&D had a +1 HP bonus for each level if you had a CON of 15 or higher. 5E allows for a +1 if you have a CON of 12, +2 for a 14, +3 for a 16, and so on. Larger CON bonuses cause HP bloat.

(4) Higher levels cause HP bloat. A lot of OD&D games in the 70's tended to cap out at level 10 or so. AD&D lifted that to level 20. Those extra levels mean more hit dice and more CON bonuses, so philosophy has contributed to HP bloat.

So really all you need to do is look at the way the rules have evolved from edition to edition. Over time the norm has been an emphasis on "player friendly" rules, which almost always means more hit points. I've been pondering running a 5E campaign where every character gets half hit points but damage stays the same. 

Greetings!

Great commentary, finarvyn!

You know, I think many people forget that AD&D didn't have any of these kinds of problems. People wigging out about how later D&D starts to become a mess or challenge problem after Level 10--well, again, AD&D kept everything tight almost entirely throughout the level 1 through 20 arc. Honestly, there were only some relative problems at level 18-20, because on one hand Players had epic power, but also the monsters often seemed gimped and restrained. That's at max level though. Lower Hit Points, smaller Hit Dice, less Con bonuses, all made Player Characters far more manageable, and over a longer campaign life span. Hit Point Bloating comes from several sources, and when you keep stacking them up, Player Characters become too uber, which then leads to the campaign becoming a mess.

Semper Fidelis,

SHARK

Quote from: SHARK on August 12, 2022, 10:34:09 AM
Greetings!

Cap Character Classes at 50 Hit Points. Remember to reduce Monster Hit Points by 50%.

Semper Fidelis,

SHARK

Or, optionally,  play a game like Shadow of the Demon Lord that quite effectively does this for you.

Regarding Hit Points
In miniature wargaming with dozen if not hundreds of figures you don't want to be messing around the details of individual figures. So combat was abstracted to 1 hit = 1 kill. When Gygax introduced fantasy elements to Chainmail along with heroes and superheroes, once way he beefed them up was to require 4 hits in order to kill a Hero and 8 hits to kill a Super-Hero.

Dave Arneson started running Braunsteins and later Blackmoor. This was found hit to kill too harsh for when the campaign was starting out. So one 1 hit to kill became 1d6 hit points. And one hit became 1d6 damage.

What the hit point mechanic never addressed was injury. Instead it is solely a measure of combat endurance. For whatever reason sounds good, when you go to zero hit points, your character can not fight. Just as 1 hit took out a combatant in a miniature wargame.

Anything said afterward is after the fact justification and doesn't change the fact that the structure of the mechanic does not account for being only partially effective at combat. Which is the point of accounting for injury for an RPG campaign.

Hit Point Bloat
With OD&D everybody rolled 1d6 for hit points. Fighters got +1 to the die roll at first level and in general, got to roll an additional 1d6 hit points every level. Other classes rolled 1d6 hit points infrequently. Fighers had an average of 8 hit points at 2nd, 15 HP at 4th, 23 HP at 6th, and a whopping average of 39 HP at 10th level.

Later editions had varying reasons for inflating the hit points of the characters (and monsters). But in 5e we know that the reason was to allow more combat options despite both 5e and OD&D having the same rough power curve as characters level.  By inflating hit points rather than muck around with bonuses, higher-level characters are distinguished by being able to do more damage in more ways than lower-level characters.

BY now there are options and combos that break 5e, but if you stick to the core rules I found that the outcome of various 5e encounters track the same as the outcome various OD&D encounters. It's just in 5e, you have more explicit mechanics for how that is played out.

Armor Class
For much of the same reason why hit points don't account for being partially combat effective. Armor Class exists as a evolution of how things worked in miniature combat.  You want as few steps to resolve combats involving hundreds of figures. So wargames cleverly collapsed figures defending themselves and armor resisting damage into a single die roll.

Take for example GURPS or Runequest. You have a specific change of succeeding on a attack roll. Then the defender can roll to defend. If made the attack doesn't land. Then you roll damage and subtract the armor rating from the damage. So if you have a weapon that does 1d6 damage hitting a target with armor with 3 protection. Then it is a 50-50 shot whether you injure the target.

If you multiply the to-hit roll by the defense roll by the odds of actually inflicting damage then you can collapse three rolls into two. A to-hit roll and a damage roll. Of course, if you try to do that in a way that is playable with different combinations of skills, weapons, and armor you going to lose a lot of the nuances that GURPS and Runequest have by keeping them separate.

So while it is more abstract using Armor Class is no less unrealistic than how a more detailed system handle it with attack, defense, and protection. But obviously not as enjoyable if you like the nuances that result from keeping these separate.

But the consequence of having that in your campaign is that combat will take longer to resolve. Maybe not much longer but it will add up over a course of a campaign.

Not, not necessarily.

It is theoretically possible to have AC and no HP bloat, as exemplified by chainmail and, say, Kevin Crawford's games.

However, having NO HP bloat requires changing other things about the game. For example, the fact that a goblin can kill you in one round with a critical hit (or remove crits entirely). Also, it might require that you spend rounds and rounds of combat where both sides miss, which can be boring.

There are ways to fix this, however (e.g. escalation die from 13th Age).

So, depends on the system, really.

EDIT: curiously, in 4e IIRC AC would increase with levels, so it's been tried in D&D; it worked reasonably well, but not necessarily the most popular choice.
EDIT: I was reading "For Coin and Blood" 2e another day, it has no HP bloat apparently.

I have decided that it's just too "computer gamey" for me; to have both a large increase in HP, and a long ladder of increases in AC.  I prefer to have a couple of meaningful increases in AC, early on for PCs; and then stop there.  Let HP top out at maybe 60 HP for PCs.

Highly trained fighters become stronger, tougher, faster, and a little harder to hit; but they can always still be hit.  Upsets happen pretty often.

Quote from: ForgottenF on August 12, 2022, 09:42:46 AMIt's weird to me that more OSR and OGL games haven't tried to address this. The only one I know of is Radiance, which makes avoiding attacks another function of the save system.

I switched my OD&D game to where the to hit value is based entirely on skill vs skill. So two fighters of equal level will hit each other 50% of the time (without modifiers, of course) and it will be very hard for a first level fighter to hit an 8th level fighter. The main reason I did this was to make armor less important as the characters leveled up. I've talked about my system quite a bit on these forums, dragonsfoot, and on /r/OSR but gotten almost entirely negative reactions to it. Despite this, I have used it in my home campaign for over five years now and it works great.

However, one of the main sources of hit point bloat isn't the combat system but, rather, the magic system. If a magic user is doing 1d6 or 1d8 per level then the fighters needs to keep up or they will be obliterated. This is why hit point limits don't actually help the situations.

No. The armor class system does not product hp bloat. I would go as far to say that is the only objective and correct answer to the question.

Hit point bloat has never been a problem in my own games. This should at least get the foot in the door of saying hit point bloat does not necessarily follow from use of an AC system.

For that matter, I'm pretty much just playing 1E by the book. In other words, I don't need a series of patches and fixes to ward off hit point bloat. And whatever way I do play is pretty close to the origins, something approximating "how it was meant to work." As common as it may be for hit point bloat to occur, in all cases I would attribute that to the edition played, house rules used, or a mismatch between the GMs vision and how the GM actually rules.

To understand how D&D's AC system actually worked, understand in 1E the baseline was assumed to be the 0th level human. They tend to be one-hit kills. Look at the Men section on the original monster manual. While there were leveled leader types, you might also see 0th levels who are more heavily armored and even mounted. You can even cross reference that with the mercenaries section in the DMG to note that, even though they don't have any "stats" per se that make them superior to other 0th level humans, heavy footmen and horsemen do in fact tend to demand higher pay.

Armor class, rather than hit point bloat, is one of the main things that distinguishes troop quality.

If you hit a "Men" section guy (d6 hit points) with a longsword, ~70% of those hits will be one-hit-kills.
If a similar 0th level is hit by a hill giant instead, its a ~95% chance of a one-hit-kill.

I'm not sure that's an earth-shattering difference. The real thing that makes the giant extra dangerous is the giant's hit tables are a lot better than a 0th level human. The giant IS a lot more likely to hit (70% chance to hit AC 5, vs 25% chance for a 0th level).

Giants having more hit points was to deliberately make them seem a lot tougher than men.
Giving humans extra hit points for being higher level was to make them seem larger-than-life heroes. That is the purpose and intent. Not a by-product of a broken system.

#1 reason most GMs gripe about hit point bloat is because they can't make up their minds what they even want. Their "preferences" are complete nonsense because they want contradicting things. They want PCs to be able to have the shit kicked out of them and still keep coming. While at the same time some pencil dick dweeb with a dark cloak and a curvy dagger is supposed to be able to one-shot them.

Old school D&D especially makes it easy enough to have the game you want. If you want heroes to be very much mortal who can be killed by the stroke of a single well-placed blade, then run a game of 0th and 1st level characters. If you want larger than life heroes who can walk around looking like a porcupine peppered with arrows and still kill a few more orcs, if that's what you think is cool, then run a higher level campaign. Either way, it's easy to implement. Because the mechanics are fine. You just need to figure out what it is you actually want.

Quote from: Eric Diaz on August 12, 2022, 01:16:00 PM
It is theoretically possible to have AC and no HP bloat, as exemplified by chainmail and, say, Kevin Crawford's games.

You not being clear by using possible in this context. It is possible to make all kinds of combat systems with a given set of elements like armor values, armor classes, hit points, to-hit modifier, skill level, etc. But there are consequences to these choices.

My point is that the consequence of D&D 5e having hit point bloat that allows the author to have characters to gain more ways to do damage as they level while keeping the odds of being successful with an attack on a flatter power curve. The part they call bounded accuracy. This means that even when you are 20th level, there is a decent chance (more than 5%) for a goblin to hit you. And a decent chance for you to miss that goblin (more than 5%).

Whether this is "good" or "bad" is a subjective question to answer on the basis of what one likes in terms of complexity and playability.


As for the utility of OD&D, I think made my opinion clear when I released the Majestic Fantasy RPG. The short answer it works and it works well. What I added were things that it didn't address like being better at stuff outside of combat and spellcasting. Even there I keep the complexity similar to the existing mechanics.

Quote from: Eric Diaz on August 12, 2022, 01:16:00 PM
However, having NO HP bloat requires changing other things about the game. For example, the fact that a goblin can kill you in one round with a critical hit (or remove crits entirely). Also, it might require that you spend rounds and rounds of combat where both sides miss, which can be boring.

In GURPS and Runequest among other system hit points mean something very different than D&D. It comparing apples to oranges.

The "whiff" problem is an issue in any system that opt to allow for a defense roll in combat. The designer has to account for that when creating the combat system. My personal recommendation is to look at how melee combat works in life and see what tactics combatants use to deal with that issue.

Quote from: Eric Diaz on August 12, 2022, 01:16:00 PM
There are ways to fix this, however (e.g. escalation die from 13th Age).

I sure it works for you and other folk. I dislike mechanics like that because I consider them game gimmicks. Mechanics that are there to make for a better board/war game not because it represent something in the setting or something that character can do within the setting.

Utimately they led to the same issue that hit points and armor class has. People forget why it was added in the first place and then start adding things because it makes sense for a game that uses a hit point and armor mechanic.

Quote from: Eric Diaz on August 12, 2022, 01:16:00 PM
EDIT: I was reading "For Coin and Blood" 2e another day, it has no HP bloat apparently.

If you need a copy, PM me for a copy of my Majestic Fantasy RPG. I come up with ways of handling the issues raised in this thread without having to jettison OD&D mechanics.

For example, knocking out a guard. For D&D (classic and new) a lot of folks, including myself, try to come up with some mechanic that allows a massive amount of damage to be done like the backstab ability of the thief. What I do instead is allow characters if they have a surprise, if they are attacking from behind, if the target is human-sized, to make a to-hit roll. If they hit then the target gets a save. If they fail they are knocked out. IF they wearing a helm their save is modified to be easier.

I also have a face shot rule but the attack roll is heavily penalized and is  it all but useless against opponents wearing helmets with facial protection?

It doesn't matter how many hit points the target has or what level they are. If they fail the save they are out cold.

Remember that in pre-WOTC D&D the amount of hp you get per level slows considerably after about 9th level. Even in 3LBB OD&D, where there is no cap, fighting-men only get a full HD every other level after 10, and even then it's on average comparable to getting +2 hp/level.

So to compare editions more directly, at level 20 the average hit points for each of the main classes is:

Cleric -- 3LBB: 38, 3LBB+Greyhawk: 34, AD&D: 62.5, 3e/3.5: 93.5, 5e: 103
Fighter -- 3LBB: 53.5, 3LBB+Greyhawk: 52.5, AD&D: 71.5, 3e/3.5:  114.5, 5e: 134
Magic-User -- 3LBB: 38, 3LBB+Greyhawk: 32, AD&D: 36.5, 3e/3.5: 51.5, 5e: 82
Thief -- 3LBB: N/A, 3LBB+Greyhawk: 30, AD&D: 55, 3e/3.5: 72.5, 5e: 103

(I may have a made a few mistakes above but they should all be in the right ballpark)

So 5e hit points at level 20 are nearly three times what they were in OD&D w/Greyhawk supplement, and nearly twice what it was in AD&D.

Point being, the hp bloat is mostly coming from the choice to give a new hit die at every level all the way to 20.