Economic as a discipline has a painfully narrow focus on mathematical modelling. Anything that doesn't fit into the models tends go get ignored: one of the reasons few economists spotted the global financial crisis is that their models didn't allow for such a crisis.

It would be silly to expect a biologist to write down an all-encompassing equation describing a cat, solve it, and thereby understand the animal. Why should that approach work on something infinitely more complex, like a whole economy?