In reply to timstich:
We only block new users from posting on the For Sale forum for their first two months on UKC. This was to stop scammers and it worked pretty well. As mentioned above, and on the other thread, spam on forums whether they be bots or people has increased dramatically in the last few months/years so much so that we completely overhauled our system.
The slightly draconian moderating you describe above ironically seems to be reserved for forums with not that much hands-on moderation. It is just a lazy system but also one that is very off-putting to new users. If you have to jump through hoops and feel like you are entering an exclusive club then it probably isn't a great forum.
Alan