Who is going to signup to a job website where you authenticate with Facebook?
http://mashable.com/2012/10/14/facebook-job-search/
http://mashable.com/2012/10/20/facebook-job-apps/
Facebook authentication was made primarily for convenience and also to help preventing spam. But of course I might be wrong by exposing peoples' names and links to their Facebook profiles (e.g. I could also allow users to choose the username which will be displayed throughout the website). Thanks for the feedback, I will think about it!