I think I - and probably many other fans - will use the term Mary Sue as shorthand around other fans because in one fell swoop I will explain to anyone who knows the lingo just what exactly it is about the character that bothers me.

I know in some deep recess of my mind that she isn't really a Mary Sue because she's (probably) not a self-insert, but it's such a handy way of cutting a paragraph of text that I don't know if I really want to stop using it, even though I know I probably should.