Yes, but that is like repairing a road full of potholes by putting out a roadside sign saying 30km/h (where you normally would drive 90km/h)
Would I prefer a game balanced around the use of a bigger party? Sure. But if Larian is going to use that as an excuse "We are not willing to tweak the difficulty for six players, too much work, yadda yadda" then my answer is "Fuck it, just give me the option anyway".
I'll take the hit in terms of challenge (or I'll just consider playing at a hardest difficulty setting, if I feel like it*. That's my problem, not something for Larian or any other forum user to worry about.
And about the fact that "you didn't see any argument of what of a party of six would make the game more fun", I can only wonder how many of these 60 pages you actually bothered to read, because even ignoring everyone else here who did the same, even by myself I spent a unhealthy amount of time arguing about it. Amount of companion quests accessible, characters interactions, party banters, more interesting group synergies, more possibilities to free a spot in your party even for sub-optimal classes or somewhat redundant ones without feeling shit about it, better loot distribution and chance to make use of greater equipment variety, etc, etc. There are countless arguments aside of just caring about "challenge" to advocate for
If your point is that you are purposefully going to ignore/dismiss any argument for it, that's another thing entirely. I can't force you to care about what I care about. But I'm not going to let you claim they are not legitimate reasons.
* About this point in particular: it depends a lot on how Larian will handle higher difficulty settings. I'm all for an increased challenge as long as monsters will stick to canonical values and difficulty will come by other means (their number, for instance). I'll fucking NOPE out of the "additional challenge" if it will come through HP bloat and increased damage for the enemies. I just don't like these as ways to raise the difficulty. They are cheap, lazy solutions that don't make me feel like I'm actually playing with the ruleset at end. Even for Pathfinder Kingmaker and Wrath of the Righteous "Core rules" is the only legitimate difficulty that exists and matters for me. Anything easier or harder is trash as far as I'm concerned.