How Luther went viral (economist.com)

Oy. Follow the money. Luther had a very rich patron who wanted to cut a peasant uprising off at the pass, and who thought that redirecting or capturing the still-bubbling Huss Protestant movement by pushing forward a new religious leader who would agree to also oppose peasant rebellions was the way to do that. Luther, unlike others who had nailed protests to the same door (including Luther's mentor) agreed. The patron was also the local head of state and could afford to pour a lot of money into the then still very expensive process of printing. That free printed matter was passed around isn't surprising; the money to print it all was what was new. Admittedly, as printing costs reduced, sooner or later something like this was eventually very likely. Ideological leadership goes to those who can afford a printing press, a la Marx.

It was a shock just how successful the strategy was. true.