Note that using user-selected nicknames is not great either. I am learning this the hard way. Example problems:

* Person used their real name, got married, changed last name

* Person used their real name, transitioned, changed their first name

* Person used characters that you no longer want to accept in nicknames

* Person used a nickname that you now want to reserve (e.g. "admin", "contact", "help", ...)

* Person used a very silly name and grew up or started using your service at their job