The only problem with this approach is if the forum did have an event which required users to recover their accounts without their password, these users might be stuck. Especially, if they haven't staked an address or have any other adequate proof of ownership.

Although, there are definitely pros of going this route. Privacy being the obvious one, but it could potentially add security in certain ways. However, I tend to think from a security stand point it's better to have an email, and make sure that email is secured, than to reduce the attack vector, but lose some of the convenience of account recovery.