Earlier quoted context omitted.
Jeff Atwood has made the same claim and it's his rationale for using OpenID on the StackExchange sites. I don't disagree, but most users won't figure out how to use OpenID. FB login is widely known but it's not at all side-effect free.
FB seems like the lowest-bar when it comes to usability. Most people have a facebook account, and are familiar with the "app needs your permissions" flow. I'm not familiar with how you write a web-app to use FB authentication - how much does using FB auth obviate the need for you to worry about user credentials?
Use FB by all means, but don't fail the auth if the user declines the extras.