I agree about white getting washed out, but I think the benefit is for the TV personality reading the text, not for the cameras or TV audience. White may be too much contrast to see the notes.
The sheets of paper used by newscasters is blue, not white, because white is too harsh for TV. Normally, the newscasters don't wear white shirts or blouses either.
White paper will appear washed out or too bright on TV, so they have to use blue or a color that will not be too harsh. The bright lights of the studio cause whites to basically disappear on camera.
