The Pitch
I understand, social login is awesome to have! But, not everyone needs to use it.
Let's take Commento* as an example. You can enable/disable 3rd party login providers. I understand that might be hard to remove individually. Instead, the ability to disable them all together would suffice.
Why It's Needed
Most companies tend to not use social login, and instead SSO. The ability to disable social authentication might be good for anyone who wants to use strictly email/password authentication.
*Commento - open source commenting platform used as example