Well it doesn’t require Fr in a uswellername to say you’re a priest. There’s no forum software to prevent me, a person without Fr in their username, from saying I’m a priest. (And to avoid any chance of confusion: I am NOT a priest. I use that statement only as an example. So to repeat: I am not a priest.)
And that’s the issue if a new person signed up and was dishonest. But we can rely on CAF to vet people after a claim is made.