Ok so basically each user will have to validated by an Admin and the newbies will have their own section where they can post until they reach 5 posts. Sounds good?
It'll be a nightmare validating each and every user manually. If you really believe it is necessary, you'll be much better off limiting Newbie accounts to a certain section for 10 posts or so.
In all honesty though, the more you try to fight criticism the harder it becomes. It will be easier on everyone if there are no restrictions from the get go.