"Developer relations" normally implies a role intended to encourage developers to use your platform. If they're just going to parrot the company line, then there's not much point in them existing, is there?
no, thats marketing.
Dev relations works with you once you are already using the platform. Don't get their intentions confused. They may be on your side with bug fixes and feature requests, but if you try to do something that goes against their company, why the hell would they be on your side?
The implication is that by having a large ecosystem with lots of developers, the company will benefit, but in this case, FB appears to have shot themselves in the foot.