On most other sites
If you forgot you username AND password and has happened to me once - cant honestly remember what email you had at the time (think it was the trainline) - you just sign up again with a new user name
Yes, but on a forum that would put you back to being a newcomer, whereas on somewhere like Trainline it's just a question of re-entering your details and perhaps favourite journeys; on Trainline it's just inconvenient to
just you, but on the Coffee Shop, it's confusing and misleading to
other members too.
And if you use IP address as unique how do you deal with DHCP or many different computers
We don't use unique, unchanging IP addresses to establish uniqueness ...