Why is online advertising such a poor stepchild? … The endless supply of online content means an endless supply of places where ads could go, which by definition depresses demand and, with it, price. Period.
The second problem is more basic still. Ever click on a banner ad? Have you? Ever? Of course not, because why would you leave what you’re doing—especially socializing—to go listen to a sales pitch? The click-through rate, industry-wide, is less than 1 percent.
— The Revolution Will Not Be Monetized - IEEE Spectrum
