Jeff Jarvis: The banning of Infowars from most major platforms is a sign of that process beginning to work. Civilization is winning, at last. Alex Jones went too far and the public, empowered by the same tools of social media he exploited, told the platforms that his behavior is unacceptable in a civilized society. The platforms—like media and like regulators—might prefer to start with a set of rules that can be enforced by government, by social-media managers, or by algorithms. But that’s not how we negotiate our standards.