I would agree that it is not found on TV or in movies, but I know a bunch of south Sudanese folks and many of them are entirely black without a hint of brown in their pigment. It is very striking and a couple of them have skin that just seems to pick up any blue in the surroundings/clothing and often give the illusion of blue-black ink pigment.
People with really dark skin are also very difficult for movie directors, photographers, makeup artists, costume designers and videographers to get use to. It takes some real practice to frame shots in such a way as to keep an entirely black person as the centre of the eyeline and show expressions without having to zoom in to far. You also seldom shoot straight on to the face as camera struggle with definition. It can be done of course, but there is a lot of ignorance around how to do it which complicates things. There are some good discussions around it on youtube with directors talking about their learning curves in this regard. Compound this 10x fold when the setting of the movie is meant to be the underdark.
Well here we are getting in to what does an imaginary race look like but I am aware of the skin colour you refer to and it is not what I regard as the Drow skin colour. Since they are imaginary people, one may legitimately differ as to what they look like, however, I think black with gray/slate highlights not blue or brown. Something quite alien to humans.