I wonder if its possible to have the game auto-balance to 6 party size - or if they would have to go back and re-balance all the encounters for the larger group.
Probably, and in theory not even that hard. Make a couple of NPC scale in limited level range (i.e. the brigand leader can go from level 6 to level 8), add a couple of random mooks to a fight, etc.
Why a "Story mode for wimps" and a "super-hardcore masochist mode" are supposed to be a fine use of their time but addressing the request to have an extend party would be the worst waste of their life?
I think "Scrubs" is the more modern term for "players of low skill level". Although I have also heard "Casual" used, but that might be MMO's only.