As justinreeves said, I choose to give that information to Facebook. It's absurd having to share all of this information to Tinkercoin so they can supposedly verify my identity to allow me to purchase $20 worth of BTC, without any indication of how they're going to use all this valuable information about me.
Stopped using Facebook auth a long time ago for this very reason and revoked access to all apps except those that I trust. There's no reason to share my entire Facebook account with everyone out there, and if that's the only way I can use their service, then I just won't use it. No big deal.
Your concern about facebook login is totally justified. If you check out the verification processes used by bitcoin exchanges and brokers, you'll find that they collect far more sensitive data than anything Tinkercoin touches.
Stopped using Facebook auth a long time ago for this very reason and revoked access to all apps except those that I trust. There's no reason to share my entire Facebook account with everyone out there, and if that's the only way I can use their service, then I just won't use it. No big deal.