Because what most people want is actually something closer to "Goal Seeking." If the system works as intended (and as you point out with the need to debug is often does not!) then defining the desired end-state and letting the system figure out how to get there, is a simpler, higher order abstraction. And it can also often be clearer to just say "ensure these prerequisites are met" such that alternative implementations can achieve the same outcome. In practice, abstractions are leaky.