Earlier quoted context omitted.
I'm not sure how addressable that is. While math could be modeled as a DAG globally, I think it is inherently linear locally (no smooth function pun intended) and incremental. Sure you could jump around, but I think at the end of day, if a student is going to progress to advanced math, they can't dodge tricky concepts. But maybe I'm misinterpreting your point. Do you have links to what you've written?
I mean this about the typical subject matter of high school (which is what this branch of the comment thread concerns). Nobody needs to learn how to graph accurate ellipses and the various facts about congruent triangles before doing calculus. You also don't need excellence in algebra to do geometry. There are some fundamentals, like being able to work with fractions, but largely high school education is a lot of par…
So you're saying there's nothing fundamental about the typical HS math sequence. I agree. But I also don't think there's that much of a compelling reason to change it, because there are going to be difficult portions no matter how you arrange it.
But I think it's not exactly true that ellipses and congruent triangles have nothing to do with calculus. Graphing ellipses is meant to help understand functional thinking, which is crucial to calculus. Those miscellaneous facts about triangles are as examples to motivate understanding of mathematical logic -- also crucial.
In other words, most of what we learn in math are really intended to illustrate underlying mathematical concepts with some level of concreteness. Otherwise, we'd just start with category theory in kindergarten and derive all other math from that :)
I can certainly understand the perception that these things are often taught solely as ends in and of themselves. I think that part of the challenge is that there is a tradeoff between taking the time to provide a concrete motivation for every math concept upfront versus saving time by dealing with math concepts in their own world to cover more ground. For instance, the seven bridges problem serves as a great motivator for graph theory (and is used very often for this purpose), but can we really afford to find a similar motivating problem for every single graph theoretical concept?