So, apparently the every-six-month or so conversation on various things that annoy in fan fiction is going around, with
Mary Sues being the focus of this particular round.
Or perhaps, Mary Sues with the definition to the extreme, which can widen itself to include almost every major female character written by a female author.
I have to laugh when I see a conversation which spirls out to embrace female fantasy characters within the definition of a Mary Sue. The simple fact of the matter is that every protagonist in fiction is going to have at least some of the characteristics of the wider definition of a Mary Sue, because in fiction, something has to happen and someone has to deal with it. And that some point that someone is going to display attributes that are bigger than life, or bigger than reality, because that's the flaw of fiction.
Real life is boring. Most of us tend to do the same things day in and day out, our lives maybe interspersed with vaguely exciting occurrences, maybe not. Fiction skips the boring parts. In all forms of media fiction skips the boring parts. Let's start with television here: how many unique and bizarre cases do you really think end up in any single ER over eight or nine years, how many odd cases land in the lap of any particular law enforcement individual, and etc? In reality, there's the routine interrupted by the exceptional, in fiction, there's the exceptional and never the routine.
And in published fiction . . . the fact that in a crowd of fantasy readers, you can pull out the names of say, Talia, Lessa, Alanna, Anita Blake, Elspeth, Margaret Alton, and various other female characters who have been used as examples of fictional Mary Sues yet have them all be recognized says something else about those characters. We read them--many of us read them or have read them. Their fictional adventures are part of our culture. In fact, look at how long say, the original Pern books have been in print.
It's a fine balance. Many readers want characters with at least a little bit of Mary Sue quality to them. There's a line to walk between just enough Mary Sue and too much Mary Sue. And seriously, that line differs from reader to reader, from author to author. Even within ourselves, it differs as we mature and learn to look at the world and other people in different ways. There's an audience for just about anything out there. Write it if you wanna write it. That's the wonder of fandom and fan fiction--somewhere, there's an audience for it.