I believe that one of the reasons that the Canadian Politics forum was for approved members only was because it provided at least a psychological barrier to visiting the forum, since work needed to be done to get in, but it also meant that the topics and discussions couldn’t be crawled and indexed, which kept the public out of it.
I get the whole moderator side of it and how that could quickly become a hassle with politics creeping in everywhere. But if that problem could be solved with assigned moderators who had clear direction for their forums (and I’m not suggesting that setting up a moderation system is an easy task that you would take on in the short-term), is there a technical barrier with this software that would make it impossible to create private forums like we had on DSLR?