Centralized systems eventually break down. In the current case, it's Facebook's identity service. As Alec Couross has described in the past (here’s the original post which outlines the problem and here is the followup) he has been beset with an endless series of people faking his account. "These profiles have shown up on sites such as Twitter, VK.com, Match.com, Christian Mingle, and most prominently, Facebook." And now, to add insult to injury, he writes, "while I have successfully had Facebook take down hundreds of profiles, apparently they no longer believe that I am Alec Couros."