I would pay extra to be able to block Premium members on my enemies list from joining my games.  A lot extra.

I don't really like blocking.  I mean I'm a bit harsh on people who make moves that don't make sense (to me) and I'm sure I've got a fair share of enemies which I probably deserve - BUT - it's not because I'd run the risk of being blocked and limited in games but because it can game the system.

Want to increase your rank on a board?  Block the top 3,5,10 or 20 people on that board and only those unfamiliar with that board would join your games.

 LOL - Camel LOVES blocking people! He blocked me when he didn't like that I attacked him!