I was wondering that - but it is just as the name says, a private area where we can talk about other things away from the General Board, so it makes sense really.
Regulars infered that by posting a lot you could get in, something that wasn't true.
Private means that it's a closed community. Which is is.
People can enter through personal recommendation from an existing member (subject to the person wanting to join having demonstrated some longevity and no penchant for idiocy) - or - by requesting access from the usergroup section of the board and facing a vote.
Yeah, actually it does apply to this area better.
So when people ask we don't have to say oh you just have to be regular - cue long evil posting spells from Pondlife.