At the core of advertising is the "idea" - almost similar to a startup. Neither number crunching nor some psychological tricks are able to replace this. In fact their purpose is in my opinion just to evaluate or optimize towards better follow up investments.
Now this might be a different story when talking about (direct)sales where you can try to quantify action-reactions related to a specific product. And for most businesses the role of marketing ("all processes for creating, communicating, delivering, and exchanging value") is far more complex than just Tweets, Facebook and Foursquare.