Imagine that you are transported by a time machine to somewhen in the depths of prehistory, like maybe 2005 or something. Imagine further that you subsequently must try to convince people there/then that one day in the future, an online service which codifies, organizes, and ranks excellent answers to very nearly any imaginable question--for free!--will be wildly less successful than one that lets people post messages of 140 characters or less. I think you would have a hard time.