I found this on a forum by an anonymous poster and I think it sums up online communities perfectly:
Once its reached a certain size, your average guild, clan, forum, or mailing-list will always implode thanks to a negative chain reaction of backstabbing, paranoia, power-hunger, conspiracies (and accusations of), etc, etc.
Welcome to the Internet.
Nearly every moderated community on the Internet tends to go the same way in the end. They turn into self-appointed cliques of admin/mod members, plus their followers, who have nothing better to do with their lives and so end up taking the "community" far too seriously. We're talking about people who would be bereft of meaning if they were no longer a part of the group.
Dare to dissent against such a clique and pay the consequences, ganged up on and maybe banned. Dare to defend the dissenters, or even point out that the hive mind is over-reacting or being a tad unreasonable, and you're guilty by association and treated the same way. Can't have reason or sanity if it disagrees with the clique, now, can we? In really bad cases, paranoia takes hold and perceived enemies of the site are everywhere.
Of course if you're in the inner circle, you get to be as much of an asshat or troll as you want to be.
The scary thing is, they seem to think that being cast out of the community is some form of terrible punishment, and perhaps it would be for them, but most normal, sane, rational people will just say "bugger that for a joke" and go get on with their real lives. Siberia and the Gulag it isn't, though the forum-addicted might believe otherwise.