Numerous attempts have been made to stop them, but sadly this software just isn't up to the task anymore. Neither Kayle nor myself has the time to look into trying to address it either, short of mass deletions of member IDs with no posts. That only lasts for so long too.
That gnarly topic with thousands of empty pages? Well, that was certainly different, but indicates that the spam prevention was working or there would have been thousands of actual posts to go with it. Needless to say I deleted the topic.
Eh.... and in looking at the admin panel, there's a whole lot of blocked registrations happening so what measures we do have are working, just not well enough.