'They' isn't a viable substitute just when gender is irrelevant.

There isn't really a label for what I identify as, but it is not 'she' or 'he,' it's somewhere in-between and neither at the same time. So even 'he or she' wouldn't apply to me: I'm not one or the other.

I _prefer_ xe/etc; but I'm absolutely 100% fine with they/them. Just don't call me he (because I'm not) or she (because I'm not). ;)

Does that make sense?

> It's a natural construct and universal to many languages.

I think this ignores too much how language imposes itself on a culture - and a culture on a language. The gender neutral pronoun is a natural construct and universal to many languages, too. We just don't have an "official" one in English.