Pushing and pulling are both functions of the fact that muscles contract. There is no logical distinction between them, i.e. a deadlift PUSHES the bar away from the floor. Anterior/posterior superior/inferior medial/lateral arrangement of the muscle mass notwithstanding, any program that trains the whole muscle mass of the body is a complete program. Squats are not quad-dominant when done correctly, deadlifts are a balanced movement when done correctly. We arrange the workouts the way we do because it works better than arranging them in other ways, which we have tried.