> Usage of singular 'they' in contexts where more specific pronouns were available was unusual until very recently

It was used whenever gender was ambiguous or needed to be protected. Now with people openly identifying as non-binary, there is not a more specific pronoun, that person doesn't consider themselves that gender. You would be referring to them as something that is not what they want to be called, and is not what their social circle refers to them as. It's confusing, especially if you know what to call them but choose not to because you're offended.

> I don't think it's unfair characterize this as an offensive move, waged by one side in a 'culture war', that was done without regard to collateral damage

I would wager, based on the disproportionate and melodramatic language, this has never actually affected you. But you are likely consuming media that tells you everyone is going to draw and quarter you if you mess up a pronoun. This is not the case. Trans people just move on, they're used to it. It literally happens all the time.