It's only new, as I understand it, as a non-binary singular pronoun. Many of those contexts have also been used for a very long time as singular pronoun where g

It's only new, as I understand it, as a non-binary singular pronoun. Many of those contexts have also been used for a very long time as singular pronoun where gender isn't at present relevant, was clarified elsewhere or in person. An example. I might send out a mail about Dave, the new hire, and introduce him in my opening sentence. I might write every subsequent sentence and paragraph with they where gender is neither stated nor implied. This is a form we're perfectly comfortable with, used to and doesn't break any grammatical law. They will be starting on Monday. Their desk will be the free one by Alice. etc. There are one or two contexts where we're not used to seeing it, so its use may seem contrived or unnatural. The only difference as I see it, thanks to the recent rise of non-binary identity, is a wish for some not to ever have someone use he or she in their context. i.e. They always prefer "This is Bob, they started this morning and they will be taking the desk next to you" over "This is Bob, he..." That, I suspect, is why some might dislike they. It's already natural in many contexts, but it's also natural to drop to he/she in a few other contexts. So it may inadvertently encourage accidental use of a non-preferred pronoun in a way that an impersonal it, or per would not.