Theatre belongs to actors. Ultimately, the theatre director has little control over the final output. When a play is in performance, it is the actor who is delivering the goods to the audience. Even the playwright has more control than the director, since plays are written directly for performance. There is no shooting script that can change things around.
Film belongs to directors.
The director has control of how the written script will be converted into action. The actors have no control once the cameras stop. When they have finished their work, it is the director and editor who will shape the finished product that the audience sees. Television belongs to writers. The most successful writers of series television today are producer-writers who own the product and control every aspect of it.