A film director, like an orchestra conductor, is the lord of his domain, and no director has more power than a director of animated films. He is set free from the rules of the physical universe and the limitations of human actors, and can tell any story his mind can conceive. That's no doubt why Chuck Jones, after creating the characters of the Road Runner and Wile E. Coyote, immediately wrote down the rules of what could and could not happen in their universe. If anything could happen (and it could), the comedy would be lost in anarchy.