The extreme investment needed to grow crops at scale has resulted in hyper specialization supplemented by fertilizers etc.

I have seen farms near me do Corn, Corn, Corn, Soy, Corn based on whatever they think will be most profitable.

In the last century, kinda sorta. In the major corn producing region of the US (I live in Iowa, the heart of the beast), crop rotation is largely reduced to choosing, based on markets whether to grow corn or soybeans on any particular acre. Dairy farmers still grow some alfalfa here and there, but the black earth midwest is pretty much corn and soybeans, full stop.

It is not like agriculture and farming was impossible without excessive production of corn.