There used to be times when people didn't care for technicalities like this because the focus was on the person's contribution to the discussion.
Now that everyone's replaceable, the popular culture desperately tries to shift focus into arguing about pronouns and terms.
Watch out, this is a road to nowhere. Forcing others to use the right pronoun won't build up your retirement fund, but will distract you from worrying about not having one. And the fact that you care about it more than about your opponent's T-shirt color could be an indication that you are being manipulated to not think about the long-term things.
This is where it crosses from insightful into conspiracy theory territory for me. People seem perfectly capable of groupthink-deluding themselves. Why cheapen your argument by postulating some master manipulator when it's not necessary for the deeper point you're making?
It will only lead to people focussing the discussion to challenge this particular aspect, or them disregarding all you've said, instead of engaging with the actual meat of the argument.
'Singular "their" etc., was an accepted part of the English language before the 18th-century grammarians started making arbitrary judgements as to what is "good English" and "bad English", based on a kind of pseudo-"logic" deduced from the Latin language, that has nothing whatever to do with English... And even after the old-line grammarians put it under their ban, this anathematized singular "their" construction never stopped being used by English-speakers, both orally and by serious literary writers.'
The same reason it ever mattered how you refer to people, politeness and respect. If someone you consider "him" asks you to refer to them as "her" it's like someone asking you to call them by their full name "Rebecca" instead of "Becky" or "Jonathan" instead of "Jon". If you like and respect them, you do as they request because things which matter to them matter to you, and being polite to them is important to you. If you ignore what they ask, call them what you want, you communicate that you don't respect them and don't want to be polite, that you want to dominate and 'win' instead.
> "Pronouns can mean whatever you want them to mean"
Only one way. A specific person asking you to use a specific pronoun for themselves is wildly different from you unilaterally and universally saying that all women should feel included by the word "him" because "him" has no meaning anymore.
That varies based on location and regional dialect. Here in the northeast US, I remember using singular they/their since the 80's. It would be interesting to know when this become popular elsewhere.
80s in Australia too, been hearing/using it my whole life.
Though with respect to 'ages' apparently it's been around since at least the 14th century but certain purists tried to stamp it out at various times (just like the singular 'you' which no one currently has grammatical issues with I hope).
I remember some people tried to get BLM into German discussions, which made absolutely zero sense, as we have a complete different history and culture. Now I see this popping up. I really hope Europe can get some cultural distance between itself and the USA in the near future. The time is ripe.