Theese spammers are on many forums and still post wherever/whenever they can you just don't see it as much because admins are a little faster in getting to threads than they are on org. I know from experience my forum was flodded on a daily basis and I was forced to become unlazy and clamped down using spam prevention tactics and tougher registeration followed by link restrictions per post count amongst other stuff.
Just takes the hard working staff here a little longer to get around to it which results in members seeing alot more spamming threads though with the help of us dedicated members we are more than happy to use that dreaded report button even if it does get us into trouble every now and again.