it doesn't always have to be nefarious. By having a FB/Google sign in a website won't have to deal with implementing login, registration, email verification, f

it doesn't always have to be nefarious. By having a FB/Google sign in a website won't have to deal with implementing login, registration, email verification, forgotten passwords, etc. Oh and even better; if they get hacked then all the hackers will be left with are hashed FB/Google IDs.