Should Unicode be allowed in usernames?

Question

Why do most (all?) websites only support usernames in ASCII? Are there any security considerations if an admin decides to start accepting Unicode usernames?

Answer 1

Or, we could just stop giving a crap about what a username looks like, and whether WE can pronounce/ remember it. That should be the USERS concern. If no one remembers you, that's your loss. And, as for name spoofing, that is almost unavoidable in any case. And yet, rarely do you ever hear of username spoofs.

Imagine a forum, imagine someone posts with an account that LOOKS identical to yours. You get in trouble, say you didn't do it, post a link to your history, see the post isn't there. Click the profile of the guy who ACTUALLY posted it, and bam, you have his profile. He's now bannable.

Having the same name doesn't mean you have the same user data. Any application that doesn't make it easy for you to differentiate two similar users is piss poor anyway and needs to be rewritten.