I totally agree too that something needs to be done. The rule the OP stated used to exist, but WGT took it out of their Terms and Conditions, and I'm pretty certain I know why. Unfortunately, WGT wouldn't police it, so I don't think it would work.
As many have said in the past, I think what needs to happen is to make it difficult for multi-accounters/restarters to gain anything from creating new accounts. I wasn't here when clubs were restricted to tier, but I do believe that is the way to go. Balls should be restricted to tier too.
Also, players should be moved up tiers based on their earnings as well as average. I gave an example in a post a few weeks ago on how winning in MPC's and Skins games should affect ones average so that players can't stay at a lower tier by hiding behind those games. Or, put a limit to how much can be won at each tier, but make it so that it is not worth staying at low tiers.