Because you can do social login the way you want to do social login.
Getting more bang for your social login buck.
Retrieving User Data
Making use of social login data.
Customizing Your Application Domain
You're not "stuck" with an rpxnow.com domain. Use any subdomain that you host.
Customizing the Social Login UI
Just set one value to true
and then have at it.
Implementing Third-Party Analytics
Want to use, say, Google Analytics to track site data? No problem.
Assigning Scopes on a Per-Page Basis
Enable different sites to
request different user profile data from users.
Facebook Progressive Permissioning
Ask for a little bit of user data now, and a little bit more data later.
Logging Users Out of Facebook
End a user's Facebook session at the same time they end
their social login session.
Adding a Custom Provider Button
Adding OpenID providers to
the social login UI.
Associating a user account
with all that user's social identities.