The article states that the real (long-term) goal of Facebook here is being an authority on proving identity.

They will be, or want to be, a worldwide provider of a kind of service, which is proving your identity. Which would tie the entire world population to their platform(s) even more.

I'm pretty sure most people have switched social media platform (geocities, MySpace, Facebook, snapchat, etc) more often than voluntarily switching banks.

Please elaborate.