Isn't this what Facebook tried to do with their support for using Facebook ID to log in at random sites all over the web? Of course you have to enable the app platform, which allows for the data grabbing ala Cambridge Analytica. Probably the reason they pushed the logins, in fact, to get more people to enable the platform - and make it harder for them to leave even with all the negative publicity about it recently!
Biting the hand that feeds IT
