Until very recently the kind of event that could induce a similar brain-state in a group of people, binding them together in terror or jubilation, had to be something like a war. This is no longer the case: a “tweet” will do it, and strangely, a war will not. And the duration and scope of this effect is far greater than it’s ever been in history.
During the Obama Presidency it became possible for vast groups of people to become aware and react in hours, and the time required for a critical mass of people to align on the same event is now seconds. This has changed the balance of power.