First round nova damage really is a thing of beauty. Running Astarion (Rogue3/Ranger5) as my main right now, and he is getting 5 attacks in first round at level 8 -- and with the sussur knife, he just goes straight for the BBEG to silence them. Gale nukes the whatever cluster is too close together. Shadowheart pops a Spiritual Weapon next to BBEG and then pops Spirit Guardians, and basically just runs around cleaning people up with the blender. Wyll, poor guy, gets the boring job of taking out the ranged attackers -- who sometimes survive more than one round.

Everyone is kitted for first round damage, and not staying power. No tank. No problem.

Imagine of BG3 had some of the really broken action economy stuff from 5e. Like a team of druids all summoning together. Or the bloody Chronomancer...