This question already has an answer here:
Why, even if you have a lot of reputation on one site, can you not participate in meta on another you have just joined? Should you be able to partcipate straight away? After all, I assume that the feature is just to stop spam users, but you're obviously not a spam account if you have tens, hundreds or even thousands of reputation points? Is it something worth changing, or is it to make sure the users get a feel for a site before starting discussion?