Moreover most sites can't help you - the URLs contain (usually) no information about you as a person. So you come to me and say "I don't know my login" or worse: "My Open ID provider is gone".
All I can do is shrug. The it becomes a matter of sleuthing: IP addresses, PayPal transactions (if you use them)... and so on.
I agree it can be better - but it's technology that when mixed with users is a nightmare.