Please no.
Many folks have beat the game solo.
I've just finished a no long rest, no barrelmancy play through with a party of 2. (And then another no long rest no barrelmancy play through with 4 Wizards)
Players are plenty strong.
The last thing this game needs is a bigger party or more damage output.
It would make combat trivial.
I'm sure Larian will include a story mode for folks who don't want the combat to be challenging.
The difficulty is the problem you're talking about.
And this problem is not related to the party size... the difficulty is a joke whatever you're playing with 4 or 1 character.
A 5 or 6 character party doesn't create new problems... I could even say that it solve a few issues even if obviously, the difficulty is still very badly balanced.
But I can't see how this suggestion could solve anything related to the difficulty issues.
