They can validate their social network graph with ease and therefore ensure they are selling perfectly valid data.

It's really disgusting to see people willfully submitting to this.

Under the guise of user protection "we've locked your account to protect it from suspicious activity, prove you are the owner" they actually confirm the identity they're not sure about and force those who use false names, pseudonyms or multiple accounts to switch to real names or risk being locked out of their contacts and data.

Reducing false accounts and such increases valuation of the data they sit on. When you buy a database of people on the black market it either comes in cheap truckloads of unverified data or expensive chest of verified detailed accounts.

It would make a good data sample for comparing user ID photos with actual tagged photos.