[PhantosP2P]

My guesses:

A) They haven't set up their business model to allow for it yet, i.e. they haven't adjusted the microtransactions of FB graal to work with PC graal; FB Credits don't translate as easily over to the PC graal's payment scheme. It would almost immediately make the PC version's business model look outrageous.

B) They don't believe their server(s) could handle the extra 100-200 or so players. This is a weak guess.

C) They haven't configured the game to work smoothly across both platforms, or feel as if PC graal connecting to FB graal gives the former an unfair advantage in terms of playability. I've tried both and I feel as if PC graal is a smoother experience, enough to say that a sparring match would go to the PC gamer if it became a duel of the pings, etc.