Besides that, in feminism it has been pointed out addressing explicitly someone female as such when their gender/sex is not a matter is a sort of discrimination (the earliest mention was iirc Barkoff 1968 in a study of English linguistic)
Which is why (I think) in some fields in English-speaking countries, there is a mass preference for using the male form in a gender-inclusive way, i.e. from [[Gender-specific job titles]]:
"Increasing numbers of women are calling themselves actors rather than actresses, especially in the live theatre. The Screen Actors Guild annually gives out awards for 'Best Male Actor' and 'Best Female Actor'."
I always thought the argument there was that insisting on gender-specific terms can, in that case, further discrimination.
It seems like we're fortunate with "user" having arisen from a natural Germanic ending rather than a Latin suffix that "usress" never caught on, if it was ever coined, as it's somewhat orthographically and phonologically awkward.
Daniel Case