Simply put, this site is a magnet for spam posts, and this is one way to limit some of the more atrocious ways they can attack the site.
As far as this clearinghouse, that's all good and fine if we could have someone monitor it 24/7. Believe it or not, the mod staff likes to ride their bikes, and do other things as well.... URL's are also a problem in the spam world, so that's not an option either, until the minimum is reached.
Greet some new members in the introductions, get ten posts, easy as pie.