No, Ragnarok (I was only kidding about the Ragzlin thing). You are wrong, and let me tell you why you are wrong. You are wrong because you are wrong. You are always wrong. No matter what you say, you are wrong. Always. I am right, and you are wrong. My rightness only shows how wrong your wrongness is.
Do me a favor, Ragnarok. Take a step back and try to stop telling people they are wrong or that they presume things or assume things.
BG3 is based on D&D 5e. Yes?
If it is, then what I'm saying is that if you use D&D 5e tabletop rules as the game was initially designed, all the encounters in BG3 are based on a party size of 5-6. This is not a presumption. This is based on me taking the actual encounters and attempting to play through them with a party of 5-6 characters via tabletop. Why is tabletop valid? Because I'm comparing the rules that BG3 is supposed to be based on with the actual video game and the point I'm trying to make is that the original BG3 encounters were obviously built based on a party size of 5-6. How do I know this? Because that is the ONLY way, using original D&D 5e rules, that anyone could possibly ever beat 3 imps at level 1. You would have to roll exceptionally well and your enemies roll exceptionally poorly, every round, in order to defeat 3 imps at level 1 with only 2 level 1 characters (3 at most with Us).
How do I also know? Because in original versions of the game, several patches ago, Imps DID have resistance, but they were still nerfed. The original battles were still too tough, so they had to nerf the imps even more so they wouldn't frustrate the players during the tutorial. If they made it so that the game started with 4 custom characters in your party, they could use proper stats (again, I've tested it with tabletop) and the imps wouldn't be impossible for 4-6 level 1 characters.
And again, I've also tested it with tabletop, and I've discovered that 3 intellect devourers is not impossible for a party of 4 + Shadowheart. It can be done. So, again, my point is that it is clear that the initial design and build of every encounter was a party size of 5-6. Then they severely dumbed down the entire thing so that you could do it with far less numbers in your party.
So, I could be wrong, Ragnarok, but I don't think so. All the evidence seems to point to the likelihood that they first developed this game as a 6 party max (including early screenshots, mind you) and they decided to try to nerf everything to make it doable for 4.
All this is to say that encounters wouldn't have to be rebalanced at all if they moved to a party size of 6. They'd simply have to use original D&D 5e stats for monsters for a party size of 6 max and then allow players to use an Easy difficulty setting if they only want a party of 4. In both cases, they wouldn't have to rework anything. They could simply create a difficulty setting that puts all monsters with proper stats based on D&D 5e tabletop rules, and a party of 6 would work just fine. Or, they could have a difficulty setting that keeps all monsters with the stats they have right now, and a 1-4 party size works just fine.
That is the entirety of my point. Difficulty setting to True D&D Core Ruleset and Stats for a 6 character party and Nerfed Difficulty Setting for 1-4 party size. Then they'd neither have to rebalance a party of 1-4 nor rebalance a party of 6.