People who were/are upset about singular they really don't understand that language change is pervasive and unstoppable. Shifts in pronoun agreement are no different.
Prescriptive grammarians cling to their (arbitrary) rules because they believe in a "pure" form of the language. That itself is a misunderstanding and just mirrors other common things some people do to divide the masses. Do not listen to such people.
As someone deeply engrained in the field of Linguistics for decades (personally, academically, and professionally), I can tell you that one of the biggest challenges in teaching people how language actually works is breaking down the preconceived notions they have about such things -- the exact notions those prescriptivists tout.
I still don't get why people have such an issue calling people what they want to be called.
You don't balk at a guy or a girl named Robin, or Alex, or any of a hundred different androgynous names....
But you take issue with "he", "she", and "them"?
Why?
My only problem, and to be clear this is entirely my problem, nobody else's, is that I'm so dumb, I frequently forget and call someone he/she when they prefer they/them. I fuck it up sometimes. I try, but decades of societal norms are getting in the way of me getting it right sometimes.
To every person who identifies as they/them please forgive me because I'm going to screw it up. Just correct me when I say it and hopefully in time my brain will stop making this mistake.
No rule in title = you must eat 196 gummy sharks,, WITHOUT A YOUTUBE VIDEO
also my homophobic mom threw away a book because the talking plant wanted to be called 'they' instead of 'it' and it's too woke for her. LITERALLY JUST A TALKING PLANT 😭
I love linguistics but it has some weird stuff in it.
Chinese doesn't have gendered pronouns in the spoken language. "He", "she", and "it" are all pronounced, “tā”.
Possession and number are done by adding 的 (de) or 们 (men) after the pronoun, irrespective of gender.
Originally, there was only one character for "tā", 他.
In the early 20th century there were several westernization movements in China. One of them included adding gendered pronouns, in order to be able to more accurately translate English texts.
Thus, 她 (she) and 它 (it) were adopted. (they used to mean other things and were repurposed).
One immediate problem that people noticed was the choice of components. 他 includes the 亻component, which means "person". 她 replaces it with the 女 component, which means "female". So some linguists pointed out that this implies that women aren't people.
The current situation is that people tend to use, 她, when there is a single subject who is known to be female. When it's unknown or there are multiple subjects they default to, 他 or 他们.
German is heavily gendered. You can still linguistically gender someone correctly but, in addition to pronouns, you also need to match adjectives. You also need to get comfortable with the gender of nouns often not making any logical sense. eg:
Moon - Der Mond - masculine
Girl - Das Mädel/Mädchen - neuter
Sun - Die Sonne - feminine
There's the added confusion that the third person feminine singular, is spelled and pronounced the same as the second person plural. The second person doesn't differentiate in gender but it's often impolite to use the singular so it's common to refer to males as "Sie".
Not to say that any of that is hard. Native German speakers constantly need to match the gender of adjectives to nouns so they're very used to it.
Russian seems to be more complicated. I recently read that Masha Gessen uses, "they". https://en.wikipedia.org/wiki/Masha_Gessen It seems that Russian uses gendered past-tense verbs. They originally used masculine verbs out of, "hoping that I would wake up a boy. A real boy" but switched to feminine verbs as a teen and stuck with that. If anyone speaks Russian well I'd love to hear more about how gender is used and perceived in Russian. Particularly from the linguistic, rather than the cultural, perspective. It looks like Russian does have gendered pronouns https://www.russianlessons.net/grammar/pronouns.php but the Wikipedia article doesn't say which they use.
Fun fact: there has been more time between the first use of singular they and today than there was between the first use of plural they and the start of the criticism of singular they
Gender neutral pronouns are just so much more convenient; I tend to use them even when I know someone's gender. I do wish English had some common-use ones that were explicitly singular, though.