I think that's basically the same reason that if you render something in your picture, you need the rendering levels in the rest of the picture to suit (don't have to match, but do have to be chosen strategically).
IMO this is actually an argument that generalizes beyond this area, into 3d rendering for example, where thoughtlessly hi-fi rendering (eg. too many frames / too much going on) hurts the artistic impression.
Really, the only way to be sure about this kind of thing seems to me to be either a) hand render everything, or b) use some level of AI.