I'm reading a Game Theory book by Martin J. Osborne, before going deep into game theory stuffs he got an Personal pronouns section to stated that: English language lacks a third person singular pronoun widely interpreted to be sex-neutral. And writers use "he" too much for unspecified sex person which he considers a hallmark of sexism in language and an unacceptable bias.

While he couldn't invent a new English word for that, he used "she" instead:

I choose a different solution: I use "she" exclusively. Obviously this usage, like that of "he", is not sex-neutral, but it may help to counterbalance the widespread use of "he", and seems unlikely to do any harm.

And he used "she" all the way in his book whenever mention someone. Interesting!