I've seen that there is something similar to this but I think this is different.

Could you make it to where a user is not able to use smilies in their posts until after they have posted X number of times, as well as not being able to use an avatar until X number of posts, signature, etc.

This could be done.

Restricting the use of an Avatar would be easiest.

Restricting the use of smileys would be tricky. But I think it could be done.
What you would have to do is turn off UBB code for users who didn't have a high enough post count.

You could probably even not display the UBBCode boxes (below where you make a post) for users without a high enough post count.

If you are interested in this, I'll write it up. Will probably be Monday or so before it makes it to the top of the list.