Personally "newbie status" prevented me from making several helpful posts in the past.  The threads weren't in the "newbie" section, and thus I wasn't allowed to post.  The problem with "newbie status" is that it relegates honest users to the kiddie pool.  It certainly has value in stopping spam posts, but I'm sure there are other ways to go about doing it.

Plus, if someone wanted to spam, they would have no trouble creating an account, waiting 4 hours, making 5 spam posts, and then proceeding on to spam the rest of the site.