Yeah, but your argument is the best argument one can make for restricting the allowed chars for user names: Unicode is easy to abuse for screwing with user names and such...

However such a restriction would be implemented - whether it would be denial of creating violagting user names, or the system automatically replacing a violating user name with a auto-generated name - as long as it is not a manual process i personally wouldn't mind whatever approach is chosen...

elgonzo‭ That's the whole reason it's not being restricted. It's easy to abuse, and hard to detect. I can disallow specific Unicode characters, but someone will just find another one. There's no easy attribute I can pick to detect what's "abusive" use of Unicode and what's genuine. If someone wants to abuse it, they will.

Don't blacklist characters or character ranges, instead whitelist character ranges. In my opinion, just whitelist characters in the ASCII range.

elgonzo‭ And then what about folks who want to use their real names? Real names aren't all ASCII, let alone usernames. Works the other way round, too: I can't possibly whitelist all safe Unicode characters, either.

Well, i guess i will look forward to see 房仕龍 here :-)

https://stackoverflow.com/a/11983015/16241416 it may be helpful to detect unicode

elgonzo‭ Without trying to be flippant... what's stopping you copy-pasting the username? Or, worst case, hover over the link and type in the user ID yourself? Not ideal, no, but neither's breaking the system for anyone with a name that's not 100% ASCII. What about Chloë? Or Ægidius? Or, indeed, 李某? See also the other comment thread on this answer.

That's a terrible UX, in my opinion. That's a reason for separating display names from user names (for example, like Twitter does), not for championing subpar UX.

elgonzo‭ I don't disagree, but so is stopping people with names that aren't completely Americanized or Anglicised from using them. Six and two threes. We should be looking at ways around this, rather than just saying "we'll block it completely" instead.

I agree with that 100%.

ArtOfCode‭ What's stopping me from copy-pasting... Because I have a quick remembrance of the name but don't have the name imprinted on hand. Doesn't happen when you comment of course, but when looking for specific users...