why do you need a director?

I was asked if there is a screenplay and a cast and a camera, why do you need a director? the director is the captain of the ship he commands the overall vision of the movie. in FIELD OF DREAMS when James Earl Jones delivers his big final moving speech. a lesser director could have just set up a camera however and just filmed him talking, but to further enhance the storytelling. the camera is positioned so you see the baseball game behind him. The screenplay only reads the dialogue, it says nothing about camera placement, but director Phil Alden Robinson positions the camera like this so when James earl jones reaches the intensity of his monologue the players behind him stop playing and pay attention. this mirrors what the audience is feeling as he speaks, suddenly part of the movie becomes part of the audience. as he courageously poetically speaks of the power of baseball. we the audience visibly see these players stop playing and they join us in beholding the power of his words, this is the power of cinematic storytelling, and the director has that power. the script itself tells a story, the score tells its own story, the camera and direction tells a story as well. put it all together and you have the essence of storytelling in movies. its why movies are so powerful. a good director knows how to use this.