This is an important aspect. People are not aware how big the difference of this is to the usual account name and password. If you want to start over and register a new account, you can have that. Not with this technology. And with the amount of data which Amazon vacuums up, there are totally legitimate reasons for this. Let's say, just as an example, that your girlfriend has bipolar disorder and you order and read a couple of books from Amazon how to cope with that, and how to help her. Fast-forward ten years. She has overcome the illness with good medication, and became your wife, or maybe you have parted ways and live in different states. This is past. But Amazon still has that information about you - a very sensitive kind of information. Maybe if this data is sold to an insurance company, she won't get health insurance. Now, closing your account and starting a new one is an option to handle, even in a limited way, that toxic data waste which is laying around.

Irreversibly tying accounts to biometric identities is a very powerful thing which can easily be abused. Think of Salman Rushdi, the Iranian writer which became target of a religios fatwa and was basically advertised to be murdered. He somehow managed to disappear. But that was years ago. In todays world with Facebook everywhere and your social graph being a different kind of fingerprint, you'd need to axe-murder your whole family and friends to get rid of that social graph which identifies you, whatever name and picture you use. AS no normal human being will do that, it has become basically impossible to disappear. And, having lived in Colombia, South America, I've known many decent and nice people who just had to disappear only in order to protect their life. This is dangerous technology.