I think the point the author is trying to make is that there may be a connection between the "moral physics" (as she puts it) in modern folktales and the genoci

I think the point the author is trying to make is that there may be a connection between the "moral physics" (as she puts it) in modern folktales and the genocidal nature of war in the modern world. It seems like the intent of these stories is to nurture a sense of innate moral superiority in the audience, often for explicitly political purposes, as she mentions with the Robin Hood story. The protagonists in these stories never go to war except against people who are true villains and have no morals at all, so it's as if war draws a line between good and evil so clearly that it justifies wiping your enemies off of the face of the earth completely. If the point of telling a story is to create a shared experience like a football game, where the audience roots for a certain side to win, then yes, it's better for the "good guys" to win. But why is that the point of stories? If we look at ancient folktales, it becomes harder and harder to root for the good guys, if there even are any. If there is a moral battle, it's between two individuals, not an army of good and an army of evil, like in Star Wars or Lord of the Rings. It's a pretty broad, sweeping claim to make, but I think she brought enough historical examples to make a strong case. We can't go back in time and ask the ancients themselves.