The point of the "napkin" isn't to be a generic Maths textbook; it's to trace up the prerequisite chain from category theory until it connects with high-school-level maths. Do you need statistics or differential equations to understand category theory?
I like the book but the contents seem to go well beyond the prerequisites of category theory—-it’s almost 900 pages.
I got the impression that the author was not simply attempting to connect high school math to category theory but was providing a broader survey of higher math. I interpreted the author’s remarks about the path to category theory as the inspiration for embarking on the project that has turned out to be a wide survey of higher math that might benefit young mathematicians.
