D&D does genuinely suck at both being an RPG system in general and also at the specific sort of dungeon crawling resource attrition game it was designed to be, and BG3 does suffer horribly for being D&D. I'd say it being 5e is even worse, but it's not like 4e was any better. 3.5e was interesting but an absolute mess, and I have limited exposure to earlier editions but what I've seen looks even worse and jankier. Like the character building is "this character is [class], number get bigger when level up, no choices, only number go up" and the combat is "you make a basic attack, because this is D&D 5e and that's what characters do they make a single attack role; magic users can make a basic attack with bigger numbers once per day, in exchange for their normal basic attacks being worse; this is a very serious and respectable system that people play for some reason."

Pathfinder is the only good version of D&D and even that still has problems from the whole "it's still D&D, fundamentally speaking" thing no matter how much 2e does to mitigate all that design tech debt and give lots of flavorful build options and things different classes can do other than D&D's bread and butter of characters either being a basic attack bot or being a worse basic attack bot that sometimes does a special attack.

Damn, imagine if instead of BG3 Larian had made a Pathfinder 2e game that had nothing to do with WotC's mid setting or bad ruleset. I vaguely remember hearing about a mod project to overhaul BG3 to Pathfinder rules since the underpinning mechanics are the basically same and Pathfinder just has better class and ability design and balancing, is that actually real or did I imagine it?