You make very good points except your first sentence of your last paragraph. GoT is clearly a work of fiction and while the author made claims about it being rooted in reality, I don’t find the idea that we shouldn’t hold fiction to the same standard as non-fiction when it comes to historical accuracy all that crazy. After all, Star Wars is supposed to be ancient history, yet we don’t criticize it for historical inaccuracies. I think a much better ruler to apply here is whether the fictional account is believable or indeed possible with constraints of physics and sociology. I argue that believable storytelling is better for fiction than historical accuracy.