How many? Just one area? If they are allowed to post in more than one area, the possible problem already exists. Only post in one section until so many posts? If so, what section would be allowed, as this would just encourage postings int eh wrong section.
I doubt Dave or Simon or anyone else involved in running this place wants to be bothered with moderating all new users until they are 'ready' to be unleashed, which is how the model railroad forum I'm involved with works, and even with an actual employee of the forum host dedicated a couple of hours per day plus a group of volunteer moderators also capable of approving posts, there can be a day's delay at times waiting for a response from a new poster. This mangy lot here is pretty good at self moderating, and while it's not anarchy by any means, the rules here are by no means onerous and the disturbances are generally few and far between.