Most sites, at least dice sites, provide either a login url (Just-Dice, SatoshiDice) or ask for a user name and password (BitDice, PrimeDice).
One of the benefits of Bitcoin gambling is betting anonymously.
There has been a couple of sites however that allowed you to login with your social media profiles, though they seem to be dead now

Do you think sites should offer the option of login via social media profile as well as the normal username/password?
If i were to choose, id rather not log in to gambling site than to link my social media account in the gambling site, because here in cryptocurrency we also value or identity so we must be careful enough to log in our social media account. If ever i encounter site like them most likely ill just ignore them or use dummy accounts to ensure the secrecy of my personality