Why should usernames be unchangable?

Question

I read everywhere (and see in practice) that usernames should not be changeable. When I ask why, \'security\' is given as a reason.

I\'ve been searching for a definitive

Answer 1

If you don't allow people to change their usernames then some people are just going to create new accounts. I don't see any security risk in this, and many apps including SO allow you to change your name. If you change the name, keep the userid (primary key) the same so all of the data links up properly.

The only danger I see is if you can change your name to an account that already exists like 'admin'.