It is ADD for sure, but there is a measured dopamine response to this type of interaction. The easiest way to understand the history of any object is through a timeline, so when appropriate I do think you are going to see a lot more of it.

From my vantage all of the modern social networks feel like the newest incarnation of the blog model, which has always had that timeline model.

Nir Eyal has some nice thoughts on it: http://www.nirandfar.com/2012/08/the-webs-slot-machine.html