[VPrime]

In our app users can sign in with Facebook, or make their own app specific account. We don't force users to use facebook.

A lot of our good (active) users are ones who make a custom account.

Another benefit for us offering an option is that we have found a place in schools.. But this is pretty specific to our app and may not apply to you at all.

We also give our users the option to not sign in at all, but limit what they can do (no community access)