It helps to rmember that as a rule, all but one mass-market social networking platform will fail. "Success" means "claiming the most mindshare". And if you're in the mass market, that means there's only one brass ring.

Any roadblocks or injuries, self-inflicted or otherwise, toward attaining that goal will not help you. Google+ certainly had much help inside and out in failing to attain that mark.

Paradoxically, this is why aiming for a specific niche can be a success, at least on its own terms. Reddit, Twitter, and Hacker News qualify on this basis.

Facebook is now actively competing against not only other comers, but itself (WhatsApp, etc.) in various guises. A battle it will all but certainly, eventually, lose.