I think all of these problems would be solved if we had our BL_ID put on our profiles when we registered our keys.
That would be a very interesting and probably useful function.
But, unfortunately, it still wouldn't help with non-authenticated accounts.
Anyone who doesn't have a key, and there are plenty of people who are quite common posters and/or prominent, could still easily be an Alt.
It wouldn't necesarilly aid in the problem.