This article in Forbes does a great job of providing historical context for the U.S. patent system. The importance of “non-practicing entities,” or NPEs, is clearly explained along with the role they play in the business cycle of Inventor > Manufacturer > Marketer.
Not all inventors had or have the means to manufacture. The practice of licensing patents (or IP) has always been critical to bringing new products to market and opening the market to inventors with little capital. Not all NPEs are patent trolls. In fact most are not. But we are now going down a path that could begin the dismantling of our patent system because, as the writer points out “…some media commentators…try to tar all non-practicing entities with the same brush as abusive patent trolls.”