The fundamentals of advertising totally changed the day the internet gave voice/power to the masses. The vast majority of the media planning/buying business has yet to wrap their heads around this. 1Cast DOES get it. Look at their content: totally fresh, up to the second, never repeating the same thing to each of their individual viewers.
NEVER REPEATING any given news article... A reach of millions, a frequency of one. No more repetition. THAT's at the core of the new metrics: identifying what ads each narrow target has seen and ensuring they're seeing a consistent brand message, but that each new impression is a different version of the ads.
That's the Occam's Razor point here -- the simplest answer is that no one ever wanted to see your clever ad more than once (OK, MAYBE twice...). As much as consumers might love your brand, they NEVER wanted 'Push Marketing', so we need ever more sophisticated metrics to improve our ability to enable us to serve up unique ad versions online MUCH less frequently than we used to on TV. This simple point is a game-changer. Only Apple (actually Lee Clow) is really getting it at the moment.