The data is squarely under Facebook's control. They are allowing other people to buy into their platform in the way Microsoft allowed third parties to develop

The data is squarely under Facebook's control. They are allowing other people to buy into their platform in the way Microsoft allowed third parties to develop for Windows. Microsoft gave developers the ability to make programs that ran on Windows with the Win32 APIs. They didn't open things up so that developers could write their own Windows-compatible operating system and compete with them. It's still closed in a way that they hope manages and minimizes the competition. "Don't build your own social graph. Use our's which we'll give you a little access to." It is very closed in that you can't friend people across services and it all has to be Facebook mediated. It's a strategy to maintain their control over the barrier to entry and extend their barrier to many applications developed by third parties. Being open means that you're on the same footing as everyone else.