In olden times courses were assigned a "bogey rating," the score a good player was expecteds to be able to shoot. It might have been 3,4,5 or more strokes above par. In that regard, I suppose you could call the course rating a modern equivolent of the old bogey rating.
Question for Adrian: I'm know there have been other threads debating the US and UK handicap systems. Out of purely academic interest, Is the CSS assigned before a round, or after it? Is it static, or does weather, or any other external factor, affect the CSS? If so, what happens if, for example, a round is suspended overnight due to foul weather, and the next day breaks sunny, warm and calm?