Isn’t calling it the “Myth of Blitzkreig” a bit like calling it the “Myth of WWII”?
Not really. I think the myth is that Germany created some heretofore unknown form of warfare which to some degree is factual but isn’t ever really challenged. It is also factual the Germans did not have particularly greater mechanization at the start of the war or that they created something from scratch and without parallel. Speedy victory has been advocated since Sun Tzu. The challenge is not to the facts of the war but to the interpretation.
It is fair to say that for many “Blitzkrieg” is used without much definition and with little nuance and to cover a wide variety of tactics and doctrine that might be better broken down and more carefully classified. What happens to the interpretation of the early war when you do that?