I disagree. I know what you're saying, and I'm down with that.
But case in point - I use Savage Worlds to run D&D. It has literally *none* of those things you cite... yet it does "D&D"... but in a different flavor. But that's because I enforce the setting conceits on the rules - not the other way around.
Feels like D&D, plays a little faster, slicker, more "cinematic", but we dungeon-crawl, hex-crawl, fight hordes of evil, daring-do, swashbuckle, etc. just like always. Only now a lot of the class stuff is merely social-stuff. And it works. At no point have I had any desire to run any other edition of D&D. Despite my deep love of 1e/2e in particular. Subjective? Sure. But my point is that any GM with a verve for a set of mechanics can replicate what they love about D&D without being forced to use D&D. I mean... I've heard of people doing Rolemaster Greyhawk... which is mind-boggling to me because of my lack of system-mastery (but I'd play the hell out of it).
TL/DR - The GM makes the magic happen. "D&D" is nothing more than the expression of some ideas abstracted by mechanics. And you can concoct alternate mechanics to do the same abstractions at will. The key is making it fun at the table. That's where the sauce is.
I get where you're coming from but I partly disagree. I think system and setting are two separate things. I mostly associate D&D with the system components (Ability Scores, d20 HP, Saves) and maybe a certain type of aesthetic or tropes (Human, Dwarves, Elves), but I think of D&D settings as transcending D&D itself--specially some of the more original ones, like Dark Sun, Planescape and Spelljammer. But even Forgotten Realms has enough self-identity and overlap with fantasy in general to stand on its own and not rely on D&D to tell it what it is.
Granted, some of those settings might be informed by D&D as a system, in terms of available classes and races, or even uniquely D&D creatures, like drow (as opposed to non-D&D dark elves), beholders and mindflayers. But D&D itself is informed by fantasy as a genre, and some of those components--like warriors, wizards, dwarves and elves--are basically universal in fantasy (specially Tolkienesque fantasy, in the case of dwarves and elves). And warriors in particular pretty much exist in every world. So none of those things are uniquely "D&D".
D&D novels hardly even follow D&D system conceits. I can't even tell which class specifically Drizzt is just by following the novels, since they give him elements of fighters (his starting class and scimitar specialization), rangers (what he supposedly is, but doesn't officially become till he reaches the surface decades later), barbarian (he learned how to rage while living alone in the Underdark after being cast out) and even mage (he wrote an amateur summoning circle and summoned a demon in one of the books, using magic knowledge he acquired during his formal education as a kid).
Dark Sun novels also do their own thing, with Sadira eventually becoming some type of Sun-Mage thing that doesn't even exist in the books, halflings being wizards and a bunch of richness and details in the use of Psionics and psychic combat that hardly translates to the rules (where psionics are basically useless outside a handful of powers that cause you to run out of PSP fast). Point being that these worlds don't rely on D&D as a system in order to populate the world of fantasy as a genre, and are mostly "D&D" in terms of branding, rather than essence.
Though, I still struggle with the question "what is D&D?" in terms of system, because D&D has changed so much throughout editions, I don't even know which ruleset should take precedence. And each edition has its pros and cons, with significant deviation following the last few editions, but also significant clean up, unification and streamlining. The only constants are the 6 Ability Scores, d20, HP, AC and Saves (which have changed in labeling between editions, but always remained similar in concept).