I don't object to Harmonix setting up Facebook integration as a means of promoting the game, allowing people to challenge each other and so on. That's a perfectly sensible idea. Giving in-game advantages for doing so (or, looking at it another way, penalising people for not doing so) is a really bad idea, though.
So here's the next question. If I set up a dummy Facebook account purely for the purposes of linking it to Blitz, do I actually get any advantages? Or are the advantages mostly obtained by spamming your friends and having lots of people connected to you who are also playing Blitz?