my own intuition on this is that making food using complicated industrial processes isn't bad or good in itself. but it is more profitable for many reasons to make food that is sweet, salty, fatty, and calorically dense, and modern manufacturing lets you do this on an unprecedented scale, so it just ends up that in practice "natural", "whole", "slow" etc foods end up being better for you.

it seems possible, although likely less profitable, to make highly-processed food that is reasonably healthy.