So this is split off from a thread from Pundit's rant,
"Only Players Roll" is the Exact Opposite of Good Design, as it doesn't have to do with who rolls.
One of my pet peeves in RPG design has to do with the effect of skill. In the real world - and in many fictional worlds - someone with expert skill can reliably do tasks that a beginner has no chance at. Examples I gave from the earlier thread include,
1) An expert professional acrobat can do a back flip hundreds of times on stage without failing. A beginner can try a back flip over and over and never succeed.
2) An expert computer programmer can write a quick program to do something that someone new to computers has no chance at. Say, find the frequency that each of a given list of names appears in a given ebook.
3) An expert locksmith can reliably pop open a door that a beginner can't get through at all.
4) A grandmaster at chess can reliably beat someone who is middle-ranked. In turn, a middle-ranked chess expert can reliably beat someone who is a beginner to chess.
5) An expert sniper can reliably make a shot that a beginner can't hit even after dozens of tries.
6) An expert mountain climber can reliably make it up a cliff face that a beginner can't get up after dozens of tries.
This is not reflected by many systems. For example, in BRP, rifle skill starts out at 25% for someone with no training, and 90% is considered high expert skill.
My preferred way to deal with this is to have this built into the skill system. For example, suppose my resolution mechanic is to take stat total + 1d10 and compare to a difficulty number (like Eden Studio's Unisystem).
I can say that a backflip is difficulty 15, an expert professional acrobat has stat total 14 or more, and a beginner might have a stat total more like 3 or 4. Then I can easily scale this, so that a legendary acrobat might have a skill of 22, and reliably perform feats that even experts regularly fail at.
CORPS (1990) is a generic universal RPG by Greg Porter, which can be a little drily generic, but has a lot of good features. I used a version of it for several Star Trek campaigns that I quite enjoyed.
I find that this sort of niche protection is actually quite fun for game-play, and indeed many RPG designs seem to downplay their skill system as niches, and instead play up non-skill abilities that are more absolute.
In the Star Trek games, say, there was no problem that other officers couldn't do the tricky engineering tasks that the engineer could. It's just like when other characters can't do magic like the wizard can, or can't fly the way the energy projector can in a superhero game.
On the other hand, there are other systems where skills are in a narrower range. Bren replied on the earlier thread,
It sounds like you are saying characters either have Engineering - in which case they can fix the Jefferies tube - or they don't have Engineering - in which case they can't fix the Jeffries tube at all.
That doesn't sound that different to saying that a character with professional level skill in Drive Auto (40%) can driver the car without needing to roll unless the circumstance is very unusual and a character with 0% can't drive the car at all. (Not all characters get all skills above 0%.) A character with >0% and less than 40% might need to make a roll under some circumstances where the professional would not - say driving at speed in the rain or some such.
I'm not seeing what you find significantly different between the two systems. Can you elaborate?
Let's say we have four characters - one with skill 6%, one with skill 17%, one with skill 33%, and one with skill 40%. They want to drive to Arkham quickly. You say that the one with skill 40% doesn't have to roll. Does the one with skill 33% have to roll? What should his chance be? What should be the chances for the others?
In my preferred system, I'd just set a difficulty for the driving task, and everyone would roll their skill against that difficulty. There's no need for me to make judgement calls about who needs to roll and who doesn't - that's handled by setting the difficulty level.
I'm not saying that engineering is a binary case of either (a) has engineering means automatic success, or (b) not having engineering means automatic failure. Some characters might have a little engineering skill, some characters might be somewhat skilled and can do middling tasks, and some characters are masters. What you can do automatically is described by your level of skill.