How different is this from medicine? When problems begin to contain irreducible complexity human reasoning starts to break. We can't test every possible state to determine which state is the best (in human reasonable energy use and timeframes). When this occurs we use heuristics and throw something at the wall to see what works.

Sometimes there just may not be a simpler theory of why something works. Or the 'simple' theory is still massively complex. Reality doesn't owe us an easy explanation.