i dont even think there needs to be a distinciton between "based on dnd" and "dnd"
everyone houserules in dnd.

Its part of DnDs dna, opposed to lets say, wargames or mtg.

i have a distinct feeling that a lot of people who hold up 5es rules as some sort of perfection, actually dont play 5e and use this as just another vector to attack something they dont like on principle.

This may not be a charitable interpretation but thats the internet for you. As i pointed out before, "feats" are an optional rule in 5e. Thats not exactly houserules but that means that in order to play the game "Properly" , i.e. how every single DM seems to run the game at least from my anecdotal evidence of /tg/ and other roleplaying oriented circles, you need to extend the basic ruleset.

Which leads me to the conclusion that people angry about larian doing just that, are just angry at larian and either dont play dnd at all, play another edition of it or simply are only used to ADnD 2E based video games and assume RAW 5e is somehow the same thing.