The next Democratic nominee will not be the latest online sensation
Since the internet became very huge, these are the candidates that would have won user polls in progressive message boards such as the Daily Kos and we can include Twitter more recently.
2003/2004: Howard Dean
2007/2008: Dennis Kucinich, then John Edwards, then Obama when it became evident be would win the primary.
2011/2012: (Nobody challenged Obama, so there was no online debate).
2016/2017: Bernie Sanders.
It is extremely likely that our next nominee will not be an electrifying online darling.
Thus, Joe Biden has a good chance. and or even Bernie Sanders, who is losing ground to Beto as a super Internet sensation, has a good chance according to my no-shiny-object theory.
There seems to be an extremely important group of Democrats who go to work, come home, and go online briefly to read the news (not to Tweet hashtags or part "diaries" in online forums).
These are the ones who will chose our next nominee.