Except that attention span is a zero sum game.
Facebook's (et al) business model success is correlated with the amount of time you are under their umbrella.
Facebook's (et al) business model success is correlated with the amount of time you are under their umbrella.
Snapchat, Vine, and other networks are not under that umbrella, meaning it's still a zero sum game. These companies are competing for your attention, for which there is limited supply.