>Why is mobile monetization so difficult? Seems like a company that can monetize the desktop experience can do mobile too.

From the article: The paradigm shift to the app model is unequivocally bad for Facebook, [...] Facebook is designed to be open all the time, to be visited in the gaps of the day or as a platform in its own right, bridging to a variety of activities related to the social network. [...] Why use Facebook to play a game, read an article, manage your photos, stream music, or shop, [...] when you can select a specialized app directly.