This. In the time I've spent on the boards (i.e. since the first great 339 exodus), there were three permanent bans that I remember well (not counting scores of spambots): OneWinged4ngel, Ubernoob, and AndyJames.
The first made himself a pain in the ass to the BGs themselves, specifically Meg, for a good while before being banned.
The second had a modus operandi similar to what people are complaining about in Sunic now, but kept it up for a longer time before finally being judged not worth the trouble. I'm not sure what the last straw was here, but I think it was the BGs getting complaints about podcast listeners being turned off from the podcast itself by the climate on the boards. This is the one I remember the least, however.
The third openly attacked and mocked opposing ideologies as well as people who defended them, and went on for a long time as well. The final straw was a personal attack on a poster's recently deceased mother that had nothing to do with the topic on hand, as I recall.
As you can see, it takes a lot to get yourself banned around here, and in each case I'm pretty sure there was a 'last straw' that pushed things across the line. BG isn't GitP, or even WotC, and this is important to keep in mind. More mods don't matter much when the climate rarely gets actually bad enough for them to step in. It's not that there aren't enough to do the job, it's that it's an emergency job.
You forgot Slate, but he was incredibly minor and his account deleted outright.
It doesn't need to be someone on all the time. That's fine.
If interested:
-- you must have presented yourself extremely maturely
-- you must be respected by members here
-- you should be "elected" by your peers
So if anyone is interested, I'll start a new thread for it.
Oww... I don't have 3 out of this requirements... Shoot... Now I'm sad.

I'm very lacking on the first one, and have no idea on the second (I haven't contributed that much lately).