Great article! A balanced overview and very accessible. One thought that came to mind while reading section two was regarding friction. It might be helpful to include a brief discussion about how reducing friction may in some cases not be desirable. After all, friction, much like a tool is neither good or bad, but does greatly affect the way we interact with the world. For example, are there instances where frictionless payments via social graph might not be desired (e.g. political donations, unwanted influence or conflicts of interest, inability to refuse payment, etc.)? Or are these edge cases outweighed by the broader benefits?