RaggieRags: Multiplayer games have the same degeneration problems as poorly moderated forums: if assholes get free reign, the others will get tired and leave, making the whole thing even more infested, which makes the rest of the smart ones to leave.
I didn't have that problem with TFC on public servers, but maybe it is because it was already an aging online game with a dedicated group of people playing it.
Sure there were sometimes jokers who tried to make their team mates life miserable because they felt that was fun, or maybe even some cheaters, but the a-hole ratio stayed quite low especially on those servers where there was a ban voting system. So if some joker kept pissing other people off, he would be voted off the server. And stay out!
Then again, I think I got banned (not voted) out of a few servers because someone with a banning power felt I played wrong. Like once I was accused of "ammo room whoring", because I was an engineer who had built the defending sentry gun near an ammo room so that I could replenish and fix the sentry gun continuously. One enemy scout/medic got fed up by not being able to run past it alone anymore, even when changing to a demoman (because then I would kill him with my emp grenade). So I was banned by him from the server. Oh well, I guess I defended my base too well.
Another time I got banned by another (enemy) admin because I had built a sentry gun inside the enemy base. The admin felt I should stay inside my own base if I was playing an engineer class. Funny, I didn't recall reading about that kind of rule when I entered the server. Frankly, I think he just came up with that rule right there because it affected him.
Third case, I wasn't banned but I got lots of complaints from a couple of players because I shot at them while they were running towards my base, and I was running towards theirs. They apparently felt that the area between the bases was neutral zone where you were not supposed to fight the enemy, only inside the bases. Again, another rule I had completely missed, and frankly disagreed with.