I don't know if someone decided to implement this policy with the new forums, but on other forums I've been on they have sometimes specifically excluded certain characters or symbols from normal users and explicitly gave the mods forum handles that included those characters to reduce the chances of someone creating a name that was similar to a mod or admin. It might even have been a default setting on these forums they just didn't touch.
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sincerely mr cabbage
Sincerely, [insert random title here]
Sincerely, Someone with logic.
sincerely mr cabbage
sincerely mr cabbage