Again. Why are you arguing against 6 member party? How does it hurt you?
You can argue all day long that party is 4-6 members, but regardless, they have the ability to do 6, it's in the game, and all they have to do is lift the restriction for the rest of it to make us happy. So why resist? Why argue?
Apparently some players actually dislike having to handle a 6-person party and prefer 4-person. For whatever reason. And also apparently it's not ok for other players to have different preferences.
Ngl, I don't dislike TB but I do hate it when I see someone say something like "TB is the way it should be and is what the old BG games should have done and RTWP should go die because personally I'm unable to handle it (or, you know, for whatever other reason)" and I'd feel this urge to start another keyboard war, but then I understand that it's their preference and it's as legit as mine. So whatever I guess.
Getting back on point, for a game like this one, having a 4-person party instead of 6 will hurt the overall experience big time. Period. You may be ok with it, but that doesn't mean it's the optimal choice, from the design choice perspective. And this has nothing to do with "amount of content you can experience in one playthrough". Honestly, if you don't even understand this...
"We make our choices and take what comes and the rest is void."