> Everyone concedes that these are fundamental, but they have been scandalously neglected, perhaps in the naive belief that anyone learning calculus has outgrown them. In fact, arithmetic, algebra, and geometry can never be outgrown, and the most rewarding path to higher mathematics sustains their development alongside the 'advanced' branches such as calculus.

I doubt one's "outgrowth of certain branches of math" is the reason math as taught to non-math majors is a castrated mess it is. It's probably the market forces that reject real analysis, abstract algebra or anything at that level or higher. It's the same reason "some programming language du jour > fundamentals of CS, IRL".