The only things that don't work as well has to do with resting. BG3 is more open world, so resting restrictions are harder. In Solasta, a Long Rest zone is limited in dungeons, so players can't spam Long Rests. Thus, potions and short rests are vital.

In BG3, having fast travel from anywhere at anytime is, admittedly, a nice to have, but as stated in the Camping/Resting thread, allowing players to spam Long Rest ruins the entire game system. See that's thread for more.

Other than Long Rests, BG3 could easily implement most 5e if not all 5e rules. I think Larian isn't doing it to make non-D&D fans happy.

That said, if they did D&D rules right, like Solasta, I really think the non-D&D fans would actually see just how fun D&D can really be. I think that's what erks me so much. They are really not giving D&D 5e a good name right now, and so many non-D&D fans are hating D&D fans because we're upset it's not more D&D 5e.