The concept to which you are referring, "direct to merchant" or as I like call it, the "Google Cash" method works fine. You can do it with most sites that have affiliate programs.
The reality is that with most, you will not be able to make money. But that is true whether you go direct or not.
You must try many different campaigns until you hit on profitable ones. Everyone has their own style and what works for one may not work for another.
Mark Roth