I just went through signing up and trying to post something with links/images at ENWorld. They have a “must make 10 posts before you can post images/urls” rule. That was very painful and has lead to people running around posting low-quality posts to arbitrary threads.
The worst part was that the system gave you no feedback along the way. It didn’t say how many posts you needed to make. The UI didn’t block-off unavailable features (you only learned about this when you attempted to submit) - this was very frustrating. The “URL” or “Image” button could have thrown up “You can’t do that until you make X more posts.” This on top of their 90-second rule for searches was a royal pain to find something to contribute to to meet the bar. All to avoid spammers.
The idea of an optional peer-approval process for n00b posts (and allowing URLs/Links in posts that requires this approval) is growing on me. Keeps the spammers at bay (ala enworld) but allows known/demonstrably-good new contributors to quickly contribute great content and advance their trust rating.