[781]

They is overwhelmingly used for plural. See how the wikipedia article starts:

> They is the third-person plural personal pronoun (subjective case) in Modern English.

And only after that:

> Although still controversial,[citation needed] and not officially accepted in formal context,[citation needed] it is also used with singular meaning, sometimes to avoid specifying the gender of the person referred to: see gender neutrality in language.

https://en.wikipedia.org/wiki/They

[cyphar]

You say that, but the singular they has been in use since the 14th century[1] with criticism only becoming prevalent since the 19th century.

Also I would pay strong attention to the [citation needed]s.

[1]: https://en.wikipedia.org/wiki/Singular_they