Sure, someone who doesn't use facebook might not care if you sell essential oils in his name on facebook, but if you are required to prove your identity, presum

Sure, someone who doesn't use facebook might not care if you sell essential oils in his name on facebook, but if you are required to prove your identity, presumably that identity is available to the service provider. So your identity will get permanently banned from the service after the first few violations, making it not cost effective for something like spamming. Its not like the captcha solving farms which sell them for 0.1 cent a piece. If, instead of just spamming, you want to do something a little more devious, like running a pyramid scheme, making a bomb threat or posting whatever your government calls hate speech - the person who gave you his identity is in trouble. It's kind of like saying "I will [digitally] sign any paper you want for $100". The ceiling for negative consequences is practically limitless. He might get away by claiming the identity was somehow stolen, but that would have to be a lot of money for so much potential trouble.