“the idea that, given time and shifting context, change is possible.”
I think that’s exactly it. Instagram and Facebook are trying to change by introducing Stories that disappear. Twitter hasn’t done that yet.
Twitter and Facebook were built for the old social web, when public permanent platforms were the default.
The new social networks — Snapchat and Instagram Stories — are built on the idea of “in the moment” ephemeral sharing — which is more true to life for how we interact with each other.
Most of the time you DON’T want to go viral.