It's a weird problem with the language. Despite many attempts, with proposals like "xe" and "thon"[0], English never picked up a good gender-neutral singular third-person pronoun. [Yeesh, that's a mouthful of adjectives.]
As recently as 15 years ago, using "they" to refer to a single individual was derided by many as grammatically incorrect. It was common in colloquial speech, but frowned upon in writing, mostly because it increased ambiguity. The thinking was that if you accept "they" as a third person singular pronoun, then sentences like the following would become unclear: "Sally and her friends went to the mall, then they left".
Of course, this is correct: singular "they" is ambiguous, and often frustrating. But it's what we've ended up with. The recent acceptance comes down to two factors: linguistic descriptivism finally overshadowed linguistic prescriptivism, and non-binary gender identity (and concern about accidental misgendering) became more prominent.
> As recently as 15 years ago, using "they" to refer to a single individual was derided by many as grammatically incorrect.
> The recent acceptance comes down to two factors
Here is a couplet from Shakespeare's "A Comedy of Errors" (1623):
> There's not a man I meet but doth salute me
> As if I were their well-acquainted friend
And the King James Version (1611) of the Bible has this for Deuteronomy 17:5:
> Then shalt thou bring forth that man or that woman, which have committed that wicked thing, unto thy gates, even that man or that woman, and shalt stone them with stones, till they die.
And these are not fringe publications, but some of the most widely-distributed texts in the English language. That makes singular "they" even older than singular "you"! I find it hard to understand the justification for opposing singular "they" even from a prescriptive perspective.
Singular "they" is very old and was not frowned upon when those were written. But there was a long period from 1800~2000 where it was maligned, particularly in formal writing. This shift was apparently down to grammarians of 18th and 19th century who promoted a "gender-neutral" "he".[0]
"Sally and her friends went to the mall, then they left" is ambiguous with or without they being singular. But, if it was normal in colloquial speech, there is no reason to not have it normal in written speech. That would be weird limitation to enforce. I am mostly surprised it was normal in colloquial speech tho.
(In this case, we know that Marak is man, so the whole thread is likely just trolling attempt.)
You're quite right about my example! I was too focused on other things and wrote a poor one. Fortunately the Canadian Department of Justice has a better example, with a legal focus:
>"When an applicant notifies the other residents, they must lodge a section 12 notice within 14 days."
("They" can refer to either the singular "applicant" or the plural "other residents".)
You're right that it's ambiguous with respect to gender, and that _is_ the point.
However, it's _also_ ambiguous with respect to quantity of people it refers to (singular or multiple), i.e. the "Sally and her friends" example. Does "they" refer to Sally, or the whole group? Having a a separate "singular-they" word available would disambiguate.
As recently as 15 years ago, using "they" to refer to a single individual was derided by many as grammatically incorrect. It was common in colloquial speech, but frowned upon in writing, mostly because it increased ambiguity. The thinking was that if you accept "they" as a third person singular pronoun, then sentences like the following would become unclear: "Sally and her friends went to the mall, then they left".
Of course, this is correct: singular "they" is ambiguous, and often frustrating. But it's what we've ended up with. The recent acceptance comes down to two factors: linguistic descriptivism finally overshadowed linguistic prescriptivism, and non-binary gender identity (and concern about accidental misgendering) became more prominent.
[0]: https://en.wikipedia.org/wiki/Gender_neutrality_in_languages...
(^ Note the "Spivak pronoun". Courtesy of the same Michael Spivak who wrote Calculus on Manifolds.)