Party of 5. 3 imps. Regular D&D stats and rules. 4 Custom + Lae'zel. Imps took 2 down, but my cleric revived them and brought them back into play. Challenging first fight, but easy enough that unless you roll REAL bad you won't game over.
Same group with Shadowheart. Faced 3 intellect devourers. Level 1. So party of 5 versus 3 intellect devourers. The barbarian was taken down by Devour Intellect. One other suffered serious injury but didn't fall.
Battles totally doable and challenging with party of 5. Totally UNdoable with 2 UNLESS you need the system.
Also started over with party of 4 in BG3. SUPER easy. Boring multiplayer because battles are so nerfed. They let me get Lae'zel for party of 5, but saved SH and she's like, "Um. Your full up. See ya.". Lame. "I know you just rescued me and all, but you have 5 people. Sorry. I'm going it alone.". ON THE NAUTILOID! Come on.
True D&D stats and rules, party of 4 + Lae'zel + SH against 4 imps and 2 hellhogs is much more fun. Right now, party + Lae'zel versus nerfed enemies. Snore.
And the worst part is, SHs excuse. "You have a large group with you. One more might draw too much attention. Best go it alone.". Then she runs off ahead of you TO THE HELM. This ain't no stealth mission. We're storming the helm. The more the merrier, and 1 more ain't gonna draw more attention. Besides, WE'RE GOING THE SAME WAY.
Dumb. Just increase to party of 6 and use proper stats like you should.
Look. I don't care what way you slice it. For multiplayer, a party of six and proper DND stats is absolutely necessary. Without it, multiplayer is severely limited. If nothing else, they need to at least allow a party of six for multiplayer.