The use of 'they' as an unspecified sex singular is not some newfangled usage.
This. I have always used it in documentation at work, things like, "ask the user if they know when the problem first happened." I work in a male-dominated area, and it's important not to use "he" as the singular pronoun by default if you don't know who you're talking about. And quite often, even when I know the name of someone I am working with remotely, I don't know their sex, because they have a name which isn't clearly male or female to me. It might be easier if we had a neutral 3rd person singular pronoun as some languages do, but the ones I'm aware of then use the 3rd person singular male form, so it's not as neutral as all that.
If I heard someone refer to me as "they", it wouldn't bother me; I would probably be upset if I heard them refer to me as "it", and I suspect I'm not alone in that preference. What they call me when I can't hear I am not too bothered about, though I suspect on occasion, it won't always be positive, so sometimes, it's best not to know anyway.
I do struggle to use "they" as a pronoun when I do know someone's sex, but if they're actually in the room, I'm likely to refer to them as "you" in any case. I haven’t come across people insisting on particular pronouns at work, but I work in a very international workplace, and in some cases, if they're using English pronouns correctly at all, that's a win. I don't reckon anyone who isn't yet completely fluent in English needs their language learning complicated further by something that many native English speakers struggle to get their heads round.