We already have something that can uniquely identify someone, and
these
sites already require users to give it to them. What's that, you
ask? Why
it's an email address.
Sure, an email address has one person, but a person can have many
email addresses, and a person occasionally gains and loses email
addresses.
I once tried to order something from a site that used email addresses
for its unique identifier. When I told it my credit card number it
said that there was already an account on file with that credit cart
number. I guess I'd ordered from them before, and they didn't want
more than one account to use a given credit card (the sanity of this
point is as questionable as their retaining my credit card number
when I *never* tick any box asking to keep my payment information in
file, and explicitly *untick* any similar boxes). I tried a different
credit card and it made the same complaint of my shipping address,
saying that that name and address already had an account as well.
The problem was, I couldn't remember which email address I was using
when I ordered from them the first time. If I had ordered from them,
it must have been at least two employers ago, and since I usually use
[email protected], but sometimes I don't (depending on
how spammy I believe that merchant may be), this means that I had a
large number of permutations of address, domain, various ways of
specifying the merchant name, and possible passwords to go through.
Since none of my current email addresses worked in the "I forgot my
password, please email it to me" form, I eventually decided that they
didn't want my money in exchange for goods and/or services, and left.
