I think that's the crux of the argument in the article. What we think of as "that norm" is largely illusory. When all the stories say X is true, then writing a story where X isn't true is suddenly unrealistic and catches people's attention in a negative way. The trouble is, in the real world X isn't true.
But we're not talking about average people in any way. The characters who populate fiction, especially fantasy fiction, are far from average. It's when this argument, "women are on average weaker" becomes "women are weaker" becomes "that woman warrior in your book is unbelievable" that it turns into a self-perpetuating stereotype that's completely against anything found in the real world.
Yeah, on average women have less upper body strength than men. But, so what? There are many women who could bench press more than anyone who posts here. There are women who could one punch ko any of us. There are women who could easily kick all of our asses. Wrap us in a bow and send us crying to our mommas. It's a simple fact. That those women basically don't exist in fantasy is utterly unrealistic.
This argument of "on average" turns into women in fantasy only being used as a relationship to a man, as perpetual victims, or cardboard characters with the threat of rape ever looming over them is not only blatantly unrealistic, it's insulting.
I've once heard an argument from a feminist, she said the belief that women are fundamentally weak is wrong. Let's face it, it's not. Women are fundamentally weaker. It's how we were made or It's how we are, whichever one you believe.
That's not the whole story however, women were brought up believing they were weak for centuries. It's only normal that female warriors, explorers, pirates are much less than their male counterparts.
So I believe, considering the real life ratio, portrayals of women as warriors or tough dudettes aren't all that rare.
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I'm pretty sure I haven't read as much as you guys but almost all series that I've read had some strong women in them.
In Riftwar Series the dark elf women are portrayed as independent, confident, powerful and maybe sometimes dominant.
In Death Gate Cycle Patryn women are completely equal man and every one of them must fight to stay alive. They are all strong and independent.
LotR obviously has Eowyn.
In Drizzt Do'urden's story, we have a matriarchal society of dark elves. Women hold the supreme power. We also have Cattie-brie.
And I think GRRM's Daenerys is a near perfect portrayal of how a scared fragile girl is transformed into a strong, fierce and sometimes brutal women under the pressure of a harsh environment
And if we look at other mediums such as comic books and manga, we have a lot of strong women although sexualized to the extremes in most of them. But that is another issue that must be adressed.