Unfortunately even WGT can't control the proliferation of unused or multiple accounts, and I certainly cannot blame WGT for that.
But I am sure they know the number of ACTIVE users, and that would be a very interesting figure to know because, as also you have pointed out, a massive number of accounts are just not active.
It would be also useful to just delete accounts that have not been used for, let's say, 1 year, but I guess there are implications regarding purchased items and so on...
Nothing that cannot be addressed by a change on the user agreement anyways.
-abq-