It's a bit tautological to say "If you remove all but x, then it's comprised entirely of x." I don't think most people would agree with your definition of ads,

It's a bit tautological to say "If you remove all but x, then it's comprised entirely of x." I don't think most people would agree with your definition of ads, either. The first iphone ads were probably showing a lot of people something they didn't know existed, but you'd be hard pressed to find someone who called the "iphone information services" instead of ads. Even in the realm of what you might consider to be zero sum ads, that might not always be the case. "Oh this car has 4 wheel drive? That's something I could actually use." Boom, added utility.