Realism is something we practice when we aren't feeling very well. When we don't feel up to the extra effort.
The sole aim of the arts of scene-designing, costuming, lighting, is to enhance the natural powers of the actor.
There is no more reason for a room on a stage to be a reproduction of an actual room than for an actor who plays the part of Napoleon to be Napoleon, or for an actor who plays Death in the old morality play to be dead.