One of the inherent problems here, and why the answer is not just "moderate everything", is the fact that it is usually pretty clear that the vast majority of people who have some 'omg MSB is so terrible' complex, are also people who, at some point....
Had an argument of some sort here, and either "lost", or did something to make themselves look even worse, and rather than just realize they fucked up or accept they're not exactly an angel, they shift gears to "DOWN WITH MSB!"
I really, really have trouble believing things like @Paris's claims about "omg there are 20 players who are terrified of being harassed by some person from MSB, actually ON GAME". It sounds fake. It sounds like any generic "we're victims, so forget/ignore every bad thing we ourselves do!" cover up.
I've yet to play a MUSH where you can't literally decide when and who you RP with.
The only cases of actual, genuine stalking & harassment I've ever seen, tend to be performed by people who are ostracized from the entire community.
Cases like @Paris's are almost always grey area "he said, she said" incidents where it's pretty clear neither side is really innocent, but they make it a "ME OR THEM, PICK!" scenario and then take their ball and wander off with some "oh I have so many friends who think like me too! they think you guys are all the worst!"
That's nice.