Well, one point that never seems to get made on this subject is "Why?" Or maybe I just don't agree with the general reasoning, which seems to centre on Corporate Greed.
A friend of mine once said that he regretted not purchasing his father's radio station when it was offered to him. Because, less than a decade later, he could have at least quadrupled his investment.
It got me thinking that the reason for the constant need to get more and more revenue out of, and less and less cost into, a radio station is because of the enormous amount of money that was paid for each of these stations. Not just to pay off the interest costs on those huge debt loads, but to start paying down the debt itself.