The chaining system would be equally dreadful regardless of whether it was DoS or is a DnD game. System has absolutely nothing to do with it.
Oh, for sure. The portrait chain sucks. The entirely system where you can select on a single character at a time sucks. The character, inventory, and merchant screens are bad. All this was bad in DoS as well, but it's even worse in BG3 because Larian hasn't designed NEW systems specifically for the needs of a D&D CRPG, they've just modded DoS's to sort of work. If BG3 was a fan mod for DoS2, it'd be some amazing work. As a $60 AAA game, it's pretty weak sauce right now.