We have a new members board, and that is the only place new members can post, apart from the meta board exceptions like hacked accounts. They can accrue post count, activity and merits, but the board restriction can only be removed by a mod or admin. This would allow a decent new member to go straight to Junior if he has made the activity. A lot of the bots and low value posters would be detected, and their accounts can be closed. They wouldn't be able to display signatures of course.
I like the idea. A controlled board in which, in order to rank-up, you can join merit contests or something like that. The best publications will obtain the necessary merits to become JR. member (yes, I think it shall be necessary to implement at least 5 merits to become JR), and, once acquired, they can make publications on others.
Each local should have, as well, the newcomers board.