well Imgine your a fighter pilot and you have 1 or 2 bogys flying around say around 30,000 ft and your around 25,000 to 27,000 ft up and you are barley getting a radar return from your on board radar, so you have to go to visual, IE Eyeballing it, well you know there close but the paint scheme blends in with the surrounding clouds and sky.
And yes at that high up it can lol, but as you just flying along all of a sudden your threat reciever lights up with a possible radar sweep or a target lock, you look around and cant see them cause they blend in with the background. then POOF! Your dead. Of course it dosent always happen that way but it is a "sound theory" as the military would put it.
Thats why some ships are painted the colors, Black, for night ops, lite blue and white for day operations, but with the white the can work in the dusk and night to blend in with the clouds.
I now i left out somethings so Im not sure Im totally correct here but this started I think pre WW2, I may be wrong on the time area or i may be close to it, the idea was orginally desgined by a pilot at the time.
EDIT: I hope I didnt hijack the thread