The problem with spinning a large aircraft is centrifugal force. The farther a piece of the airframe is from the center of rotation, the larger the forces on that piece. If the cockpit is 20 feet from the center of rotation, the forces on the pilots would be extreme and could make it impossible to move, let alone control the airplane. The forces on the engine pylons and tail would similarly be extreme. If a large aircraft like a 747 got in to a spin I believe it would tear itself apart.
If anyone has a video of a large aircraft recovering from a long multiple rotation spin, (not just an entry) I'd love to see it.