I think the majority of the people banning others, because of their ID number, are those that were harassed because of it in the beginning. Now it's like a vicious cycle or something.
The servers I tend to go to, mainly servers by people who I played RTB with before Retail, are usually the best ones. They, I guess, tend to understand more the good from the bad by giving them a chance to prove themselves. At least from what I've seen.