Although more weight can be moved with the "king of pressing movements", the bench press, the shoulder press requires and develops strength through a more functional movement pattern.  Generally speaking, the functional movement of weight involves picking it up, squatting with it, or moving it to an overhead position.  Outside of the gym, when was the last time you laid down to lift something heavy?

Workout

Shoulder press 1-1-1-1-1 reps