Using 'they' for an unknown gender has nothing to do with people 'identifying' as they, or anything modern.
It's never been 'he', except in sexism such as 'when the doctor comes he will examine you' (with the doctor's identity and hence gender unknown, but assumed male by profession).
It's never been 'he', except in sexism such as 'when the doctor comes he will examine you' (with the doctor's identity and hence gender unknown, but assumed male by profession).