It's an interesting point. Trying to use language in a way that doesn't come naturally is inhibiting and distracting. It's a strain. All the more so when there are people waiting to come down on you like a ton of bricks if you slip up. Plus the guilt trip they're trying to lay on you. ("If you refer to a male person who isn't present as he, you're responsible for his suicide" and similar nonsensical propositions.)
Sod that. I'm not playing.
ETA: Yes, the informal use of "they" in very specific singular situations is quite longstanding. However these situations are ones where there's no doubt about the meaning (for example a single person seen from so far away that you can't tell the sex). Using "they" when he or she is expected, and when the person's sex is known, is just a silly affectation.
I read something which I took for a clever spoof, but others said it was serious, ostensibly written by a transwoman, intimating his intention to bring his kitten up gender-neutral. He constantly referred to the kitten as they, and people kept saying, I thought you had only one kitten?
For goodness sake, was he entirely unaware of the word "it"? That would be insulting if used for a human being (unless you're Bel in the Miles Vorkosigan books), but it's commonly used for an animal whose sex you don't know. A little aside. Over 30 years ago I was commissioned to write a cat care book for the Christmas coffee-table book market. I referred to the hypothetical pets in the book as "he", on the same principle as Meadmaker's example. When I got the edited manuscript back the editor had changed every single he to it. I threw a total strop. Nobody calls their pet it. This will put off the potential buyers, it's impersonal and unnatural. In fact if you're going to do it, you can take my name off the book. She compromised by using "he" and "she" alternately, which seemed a bit silly but I let it go.
Conversely I was speaking to a French tourist once who told me that her French teacher had told her class that in English the word "it" was always used for animals. I had to spend some time thinking about it, before explaining that this was common usage for an animal you had or felt no relationship with, but that he or she was de rigeur for animals you were in some sort of relationship with. I explained that as a vet, doing consultations, one very important thing to remember was to check the sex of the pet before the owner enters the consulting room, to be sure to say he or she correctly. And if that's not possible for some reason then at a very early stage in the examination you make sure to find out. It's actually quite easy just to have a quick peek and say to the owner as one does so, "are we a boy or a girl?" (I note that Jori's vaccination certificate, issued to his breeder when he was a baby kitten, has "boy" scribbled on the front of it.) Nobody ever refers to a pet animal as it, and even farm animals are generally called he or she if you know. Although I have seen farm animal case reports that veered from he to it and back again in the course of a couple of paragraps. (A couple of years ago on a rideout I was in conversation with another rider who had a very nice horse who just looked girlish. I referred to the animal as "she" a couple of times and the owner laughed and said "did you just misgender my horse?" She apparently got this all the time, everyone always guessed wrong.)
Another related point. I've been reading up on some linguistics topics recently, and one thing that fascinated me was the research on the order in which people learn specific grammatical points in a new language. Apparently the third person singular is always the last to come, and some fluent speakers who use their new language daily for many years still get it wrong. ( I think this must be in cases where the usage isn't the same as the person's native language, because I don't have a problem with il or elle, er or sie, or e or i.) I then heard an account from a woman whose mother was, I think, Hungarian. In that language the third person singular is not gendered, any more than the second person is gendered in English. Although the mother had married an Englishman and lived all her adult life in England and was completely fluent, she regularly called her daughter he or her son she.
Language usage is a very deeply learned thing, and it seems that the third person singular is a particularly knotty one to change. There's a lot going on here, and just saying airily "do it to be kind" (to Jonathan Yaviv? I don't think so) is not particularly helpful.
