I doubt one person is able to do this, it's most likely a team of abusers working together.
It's not so hard, since we have no Ip restriction is quite easy, one bot to rule them all.
If I'm not mistaken, Bitcointalk does have an IP "ban" system that will lock accounts if too many accounts have been created. After that, it will ask you to pay a fee which you have to pay. I'm not sure if you do have to pay after that for more accounts (if there is a reoccuring theme here) or you are allowed to make as many accounts as you want to.
Well thats IP "evil point" system and not Ip "ban" system. One can easily pass that if they use VPN to alter their IP and escape fthe IP "evil point" system.