No, it's correct English and has a long history of use and appears in famous writings.
>The singular they had emerged by the 14th century and is common in everyday spoken English, but its use has been the target of criticism since the late 19th century. Its use in formal English has increased with the trend toward gender-inclusive language.
Thanks for linking. According to Wikipedia it does seem that in American English gender-neutral “they” is a bit of a touchy subject, in that some people and style guides find it unacceptable, so I took note of that. I’ll keep using “they” though, genderless speech is a neat language feature (and it just doesn’t sound wrong to me in English, like gendered pronouns do sometimes).
Basically singular they is used by everyone because it sounds and feels natural in many contexts. It's only a touchy subject when people assume you are using it to be "politically correct."
Style guides are changing, Washington Post just changed theirs to allow singular they.
>The singular they had emerged by the 14th century and is common in everyday spoken English, but its use has been the target of criticism since the late 19th century. Its use in formal English has increased with the trend toward gender-inclusive language.
https://en.wikipedia.org/wiki/Singular_they