You can find critics of its use that are almost as old as its use. Oddly, for some reason critics of its use don’t seem to show up… Until it started being used.

Poets and authors have been artistically butchering, changing, and shaping language for as long as language has existed. This is neither an argument for nor against any particular change. Just look at the nonsense that James Joyce did.

I have a non-binary partner and I respect their pronouns, but personally if I cared enough to change my pronouns I would be more comfortable with “it” to avoid any confusion when discussing a mixture of singular and plural nouns. Heck, if I was going to make my own language from scratch singular vs plural pronouns would be much more commonly used while gendered pronouns would be reserved for specific scenarios where gender is relevant.