Well, the thing is in 5e the campaigns are based in 4 players, the monsters and creatures like the gnomes, not-green-goblins, cambions, Ilithids, dragons, etc look exactly like ingame in the PHB books, over 95% of the actual ruleset of 5e is being implemented ingame, some references about the lore, like Astarion having problems with running water or the question "What are parents?" of the githyanki Lae`zel; skill mechanics or action-based combat,etc
I understand that feels different from 2e of BG games or 3e of NWN games, but that´s how it is 5e now. You could like it or not, but it´s still D&D.
Believe me, Larian could mess up the game in many ways, but in lore or mechanics if they do something, they have permission and direct approval of WoTC. they´re very invested in the project.