The fact that usernames can break anything speaks to something profoundly wrong in general. Why should usernames be leaking into URLs instead of a surrogate ke

The fact that usernames can break anything speaks to something profoundly wrong in general. Why should usernames be leaking into URLs instead of a surrogate key? I mean, barring some tricks that could break layouts during rendering if people got really creative with them, why isn't any valid non-blank Unicode string a valid username? Reminds me of this xkcd: https://xkcd.com/1700/ https://xkcd.com/1700/