People wouldn't get paid because they're not earning merits, which would then drive them to buy merits.  People would earn a merit on their first post of the week and then not have to post again, which is a waste of money for the campaign. 

This isn't a horrible idea, but the only thing I see are the drawbacks.  I like what Yahoo62278 is doing better, which is to require a minimum amount of merits before even being accepted.  That weeds out a lot of shitposters.