I haven't been around in PC for long and I would so much want a forum for the "serious" discussions, but I've seen it happen to all the forums I've been in, contanious flame wars. Discussions that turn into debates, then into flame wars and offending someone on personal level. There are people who just long for a reason to flame someone and they are not afraid to use every chance they get. No, not everyone is like that and it's the mods' job to "supervise" the stuff, but frankly, there a lot of people who like to flame, for some absurd reason that is unknown to me.
Moderators can't always be there, when you need them, and with a place for serious discussions turning into multiply flame wars filling mods' hands with work. End result, lots of petty arguments, someone might get hurt on personal level and a lot of warnings and possibly bannings.
I've seen this happen in a forum that I moderate. Well, I don't moderate that particular sub-forum that held the discussions, but there were some good discussions about religion and the current Pope and George W. Bush and that was fine. I was away for few days and when I came back, the moderator forums were filled with topics of banning or giving a warning to somebody. People were permanent and temprary banned, multiply warnings were given to several members. And that wasn't the top, some of the moderators revolted, as they thought it was unfair to lock these topics, and as a result, they resigned.
I'd like to see a test run of month or something, sometimes these things work, but mostly not ;)