@david lyga,
I write for a living and I don't care.
This is prescriptivist at best. At worst, pedantic.
Writing and speech are communications. They need to be understood. Native English speakers understand the singular use of the 3rd person plural pronoun
they.
"Steve, you got a phone call."
"Well, what did they want?"
The term is well understood.
And it has nothing to do with women's liberation.