One of the things that I liked about the book was the idea that if something has obtained that "historical myth" status, there's a reason for it. It resonates with people. The idea isn't necessarily that certain events are more true than others, just that certain interpretations of events have gained more historical traction, while others have been forgotten. I think a major point of the book is that the forgotten stuff is worth remembering. Not throwing over all your previous conceptions of history, but, as you said, adding to our understanding.