The logic is based on login by email address and password ...
While you could have your code customized to use a different method ... this has been tested to be tried and true for years ... if you change that and do not test the results correctly you will have problems ...
Uniqueness of a name vs email address means ... the 5 Joe Smith's cannot have joesmith as their login ... now you have 5 customers and their wives ticked off ... having to use joesmith2 joesmith4567 etc.
What's your email? Not a lot of answers to that one ...
What's your login name? long periods of silence to remember ... :cry: