This article is confused and makes all sorts of horrible assumptions. In short, the author seems to believe that the only way people make money off free software by adding "differentiating" proprietary software to it. Since the whole point of the GPL is to prevent people from making the software under its purview non-free, it shouldn't really be surprising, then, that the author finds it a huge pain in the neck. Personally, I'd say the license is a success, and I suspect a lot of the companies making money from GPLed software would agree with me.
-- Brett Smith, License Compliance Engineer, Free Software Foundation