1. Do you mind that your users may get locked out of your product for violating Facebook's real name or one-account-only policies?
2. Do you really want to phone home to a publicly-traded advertising company every time someone logs into your site?
3. Social auth asks users to make a significant trust decision before they can even begin to engage with your product. Are you OK with that friction?
Passwords are a pain in the ass, but there are alternatives without the downsides and centralization of social auth. I personally work on Mozilla Persona (https://persona.org), and I'm more than happy to personally help out anyone interested in exploring it for their project. My contact info is in my profile.
More pragmatically:
1. Do you mind that your users may get locked out of your product for violating Facebook's real name or one-account-only policies?
2. Do you really want to phone home to a publicly-traded advertising company every time someone logs into your site?
3. Social auth asks users to make a significant trust decision before they can even begin to engage with your product. Are you OK with that friction?
Passwords are a pain in the ass, but there are alternatives without the downsides and centralization of social auth. I personally work on Mozilla Persona (https://persona.org), and I'm more than happy to personally help out anyone interested in exploring it for their project. My contact info is in my profile.