I think it's safe to conclude requiring merit is NOT a solutation against spam, if it's an automated system that accepts anybody.
When anyone who can convince a team to hire them can become a manager the system will fail. Likely it will lead to more abuse down the road... where does the "bribe" taker drop the Merits off?
I have been in a few of Yahoo's campaigns and while not requiring merit for everyone, if you had a certain amount it netted you better payment. There are countless ways to try and improve the system but without there being any enforcement behind it they won't matter. It would be nice to require a certain amount of received Merit to carry a paid SIG, but again that would require further moderation, which genrally isn't going to happen.