Watching TV in a pitch black room is very bad for your eyes, but we all like a darkened room. So, rather than turning down the room lights with a dimmer - lights which are not neutral in color and could make the accuracy of the TV appear off - some enthusiasts like to install lights behind the TV which light up the wall behind the TV with a neutral color light which ultimately enhances the accuracy of a good TV.
The one drawback to all the efforts to get truly natural bias lights to mount behind the TV is that few people have neutral colored walls behind their TVs. The ideal is a true non-color gray paint for the wall behind the TV so the illumination from a truly non-color bias light will not impact how your eyes see color on the TV. If the wall is painted any shade with color (as damn near every household paint color happens to be), then the effort for a pure white (6.5K) light is somewhat wasted.