Okay, so I'm making an assumption here. I'm sorry if it's wrong.
99% of the time I've noticed that when people bemoan the singular "they," they're generally upset because some English teacher, parent and/or other grammar-correcting type-person hammered into them it was wrong.
Hard. So I'm assuming this is what's going on here, and my answer will be framed accordingly.
Firstly, lots of people like to assume this is a new and edgy thing, PC going overboard or some such nonsense. This is terribly incorrect.
In fact, the singular "they" has been in use for literal
centuries. The earliest documentation of it's use is in 1375, in the medieval romance
William and the Werewolf. That it showed up in a written document also implies that it had been in accepted use much, much longer than that. It wasn't until the 17th century that a lot of grammar-correctionists started laying down the law about "they" being a plural pronoun and stating that the singular "you" should be used instead--ironic considering that "you" was also once a plural pronoun that later became singular. And by "later," I mean, in 1660 George Fox wrote an entire
book stating that anyone who used the singular
you was an idiot or a fool. It doesn't take that long for language to change, or for a new generation to shrug off what an older one swears by.
Though teachers and a whole bunch of know-it-alls put the smackdown on the singular "they," there is evidence that it has never truly stopped being used. Examples of it can be found in many written works from the 18th century on, the most hilarious of which was a dude mansplaining to three women in the
New Bedford Medley in 1794 why singular use "they" was awful and wrong (and insulting them while doing so), to which they tartly replied that they were using it deliberately to conceal gender and if he was so smart then he should come up with a better term. To my knowledge he never replied.
It's been so common it even shows up in classic literature by authors like Jane Austen, Henry James, Charles Dickens, and F. Scott Fitzgerald.
So what did the historians replace the singular "they" with? Why...the "nongendered"
he. This is where humankind became
mankind, when we started referring to every animal of unknown gender as "he," when the use of language started sweeping women and non-binary people out the door, then firmly shutting it behind them. Language follows thought, but thought also can follow language--if you don't believe it, then ask why the CDC is no longer allowed to use the phrase
global warming, but must instead resort to the much more friendly sounding
climate change, or why an anti-gay hate organization might pick a name like the
American Family Association? We react powerfully and unconsciously to words and phrases--it's why well written propaganda and advertisements are so danged effective on us.
But the worst part was that "he" was never really used as a universal pronoun. Instead "he" implied and was used as male. For example, if one was writing about a nurse, secretary, or other job largely seen as feminine work, people defaulted to she
even when they didn't know the gender of the person being written about. On the flip side, when talking about jobs seen as traditionally male--soldier, president, doctor--people defaulted to "he," again, even when the gender of the person in question was unknown. This isn't an old problem, this is something that started almost right away and has continued to this very day. You might recognize this particular topic, since it's one of a slew of conversations that are currently being held about the
many problems surrounding trying to turn an
obviously gendered pronoun neutral.
One of the compromises we had for a while was using "he/she" in writing, but not only was the awkward to read, but it was extremely cumbersome to try and say aloud. For example:
Teachers need to catch their students' attention, so he or she needs to make his or her presentation as engaging as possible. When faced with mouthfuls like that, most people just dropped a gender. Usually the female one. And now that we're acknowledging that humans can and always have come in more than two genders, this compromise becomes even more limiting.
And that's the heart of the issue; we have never come up with a better term. We've tried--there must be several dozen suggestions running around out there--but many have problems or just never caught on (for example: zir/zim is too close to a misspelled her/him or sir/him and brings those pronouns to mind). The singular "they," on the other hand, never truly lost traction. It's been in common use through almost three centuries of various authorities doing their level best to make it disappear, and in accepted use five or more centuries before that.
Honestly, you have seen it, read it, and probably even
used it without realizing it. The very fact that you made it through school, read classic works by some of the authors listed above, and likely never noticed it tells me that, like many people, you were so familiar with it's usage as to make it virtually unnoticeable. I mean, until a language movement swooped in out of nowhere and threw a great big shiny spotlight on the term.
I think of the singular "they" like a rubber band--attempts to pluck it out of the language simply ended in it snapping back, and giving a lot of perfectly intelligent and wonderful people's ideas of proper grammar quite the sting when it did so.
Considering the word's history and how things are going I'd say to give all the English & Grammar Police from your childhood a middle finger and find peace with the word. Not only is it not going anywhere, but it never really did. It's been stealthing through our language the whole time, looking at us with woebegone eyes and asking if we finally consider it a good puppy and can it come out of the doghouse now?
We just...relented and said yes.
But honestly, I do get hating certain words--I
despise ginormous. But
I'm fine with moist. Go figure. (Also, "ain't" is my favorite legitimate contraction ever to be forgotten--I might be a bit of a word geek.)