Doesn't make sense to make it mandatory to login using facebook or twitter in a gambling site. That sounds fishy to me. But if I badly want to try out a gambling site I might consider making up a fake twitter , google or even a facebook ID. Will never you my real one!
Agreed with you it doesn't make any sense to account our personal social media account to gambling sites which could be risky and person can access to our profile easily. I never used my social media account to any gambling sites always use my email account and password to get access.