Interesting observation.
Well, if personal information from Google or Facebook is that reliable, why don't the exchanges use them? There are people who will never use phones camera, finger prints sensors or biometric authentication features on their phones.. . Internet devices won't have much on those kind of people. This is probably why verifying users identities via social media isn't used much.
I disagree. Even if you don't use any biometric authentication or your phone camera -- until you actually have a phone, you're translating data about your location (whether you use VPN or not), installed apps and so on.
It's not that I'm all about conspiracy, but prove me wrong.
As for verifying identity via social media -- it may not be using cause this isn't your
passport. But that doesn't mean, that you cannot be identified as a real person by your phone traffic.