groundpwndr or whatever is right, deleting main accounts is usually a bad idea. once someone loses their main account, what else would they have to lose? probably nothing. IP bans don't mean shit in most cases; if they don't have a dynamic IP, they can use Tor. so basically they can do whatever the fuck they want because there are no real consequences left.
about the superhaxor bullshit: so what? damn skippy anyone can build a botnet and DDoS NG off the internet for a while (hell, the servers shit out on a regular basis anyway), and with the right technical knowledge and a bit of social engineering, hacking accounts is easy also: just set up a shitty NG community site and wait for idiots to flock to it and use their NG passwords as their passwords there. (anyone remember NGChat?)
and about the pepsiclock thing, I once got locked out of my account for far less than coordinating an across-the-board award fuck. (Mozz Day. I was one of the original organizers, and I submitted 10 movies for it on various alts)