Most board users keep one account and change their displayed names because they think that a different displayed name will look better.

We offer that option. Very few boards do.

Others simply stop using an account, or forget their usernames and passwords, and create a new one.

A few are using the boards for reasons other than what it was intended for, to find dates, exchange things, or to make real life friends... and this kind of activities may make members change their usernames when things go wrong :-)