I have neither played BG1-2 or PoE
This is all you needed to say.
This shouldn't have to be a prerequisite to have opinions on something new vs old.
You're making claims about something you have never experienced. It would be ridiculous to walk out of Phantom Menace and say "Well compared to the old Star Wars movies I never saw, this was way better." I can't imagine what makes you think that's appropriate to do with a game or tabletop rule set. You even admit you have limited experience with 5E and (very likely) none with AD&D. So you just have zero context with which to discuss whether or not BG3 fits the series or represents a more or less well-designed transposition of tabletop mechanics.
Ex: It's utterly meaningless for you to call a game's design "not streamlined at all" when you haven't even played the game. It's just noise.