IIRC from our previous conversations, you view hit points as "meat". Meaning that a 100 hp fighter can survive more physical punishment than a 10 hp fighter. Under this interpretation, using rigorous application of the scientific method, one could arguably determine exactly how many hp that fighter has (from within the game world itself).
However, if you recall, I view hit points as nothing more than a (convenient) gamist abstraction. Within my interpretation, there are no implications of hp on the game world, because they don't exist in the game world. No application of the scientific method (in the setting) could ever reveal the existence of hp, because they don't exist there to begin with.
I want to regard HP as the latter, but they are prevented from being that, because the game rules hard-block it, even if you don't regard them as "physics" that apply off-screen, they do apply on on-screen, and they prevent stuff that's a really, really basic component of really common fantasy settings, like uncontrolled falls killing or seriously injuring people, or people being knocked out or killed in a single blow. The fact that in D&D, all on-screen combat is weardown combat, and that there's basically a trinary state of being "basically fine", "dying" and "dead", with no injuries, and immediate returns to full effectiveness on the slightest healing, and where one night's sleep will fix literally anything
does limit what D&D can do fantasy-wise, even just applying on-screen (and assuming off-screen things are very different).
Regarding "Vancian" magic, it's only Vancian in the loosest sense in 5e, and sorcerers in particular are quite similar to mages in much of fantasy. They know certain spells. They have a finite amount of magic they can generally use before they exhaust their supply. Wizards are the closest you'll find to Vancian magic, and even they are further than they've ever been from the writings of Jack Vance.
Of course, there are usually specifics to a given magic system that it doesn't duplicate, but that's literally impossible for a "generic" magic system. If you want to duplicate a specific magic system, you would need to design a system specifically for that. Worlds Without Number, GURPS, and Savage World (as well as every other big net game out there) have essentially the same "issue" with their magic system.
This is disingenuous, though it may not be intentional on your part.
D&D was never close to Jack Vance's take in any edition (as has been much discussed), so it's a weird and pointless semantic argument to point that out. The term Vancian applies regardless.
I agree that it's not possible to have a truly
universal magic system (god knows people have tried), but I don't think it's remotely true that you can't design magic systems that are broadly generic and whilst they might not be a 1:1 match, are say a 0.8:1 match, whereas D&D's bizarre magic system isn't even going to be a 0.1:1 match with most games. Either using an exhaustion-based or spell-point based system with casting checks and broader spells would get you a hell of lot closer to about 80% of fantasy media.
(As an aside, you could probably have a decent discussion about exactly how to fix this in another thread, because I don't think it would be impossible, esp. as most magic systems in fantasy media fall into about three categories none of which is even slightly similar to D&D's approach.)
Even WWN with it's intentionally-peculiar system at least has a properly worked-in spell-point based caster (and you can bring in Psionics from SWN). You'd have a hell of an easier time running DS with WWN than 5E D&D (indeed I've seen some people discussing how they're doing just that). And WWN isn't a "generic" system, it's a specific one.
GURPS is of course generic, but I will admit, I am drawing a blank of its magic system entirely so can't comment. SWADE's magic system is going to work better for a lot more fantasy than D&D (IIRC, it's been a while).
It's certainly not true to suggest most/all fantasy RPGs have the same issue to remotely the same degree. It's a risible claim that relies on us ignoring obvious differences. D&D's system is hugely incompatible with fantasy in general because it's so odd.