Honestly don’t give two toots if some people decide to go out of their way to take offense at such a term.
I don’t go out of my way but duly noted that you don’t care that people don’t appreciate such a sexist term.
It’s a descriptor for a type of character. Wesley Crusher was a Mary Sue.
The amount of references to male Mary Sues are about 0.005% of female Mary Sues. That’s precisely why it is sexist.