Woah, wait, stop. It was jarring that the author glanced over this. You can't dismiss the exceptional just because it's exceptional. You can dismiss the exceptional when you understand why it's exceptional and can make an argument for why it is irrelevant.
In other words, why are social games and Busted Tees successful? There's really not a lot of obvious crossover in what they're selling. One possible explanation is that they're "impulse" purchases which mesh well with a social environment. Social games mesh because Facebook connects you to people and once you're connected you would like to do something with them. T-Shirts seem to be a similar sort of social sharing, à la Pinterest. This seems to imply a lesson: if you wish to market on Facebook you should probably be marketing with Facebook. GM probably didn't have success because what they were doing was really orthogonal to the Facebook experience.
One thing that people tend to forget is that most ads are really bad. Just because naive advertisement doesn't work on Facebook doesn't mean all advertisement doesn't work on Facebook. I wouldn't count Facebook out so quickly -- they just need to pivot their advertisements to make them more lucrative for all involved.