There are people who identify as neither male nor female and there is no precedent or widely accepted alternative to describe them. They/them is preferred to the only other singular pronoun: it, as that is seen to be dehumanizing.

There are numerous alternatives, but none have seen widespread adoption.

I have no problem using whatever pronouns people want, but when they start using a plural pronoun to refer to a singular human being, I agree -- that's shitty grammar.

or confusion. I too dislike They.

And it seems to make little phonetic sense in English construction. Ze would seem to be a superior choice as a subject. And having both both Zhim and Zher--or choosing either or an object noun--would defeat the purpose of gender neutrality.

zhim, zhim, and he.
zhim, Jim, and who?