Alright, but the question is "why would someone want to log in with Amazon"? There's no social network attached to your Amazon account. It seems like it would be an odd choice of identity provider, unless you are a store and already using Amazon's fulfillment services.
> "why would someone want to log in with Amazon"? > There's no social network attached to your Amazon account I think you answered your own question.
I'll finally start using "Log on with" if I can use Amazon.