What I'm trying to say is that there was such an evolutionary environment. The 60s were full of deadly riots mobilized by some minor rumor - the Watts riot, for example, killed dozens of people in response to rumors of police misconduct in a drunk driving arrest. We just don't normally think about it this way, because when we look back at history the Watts riot is always interpreted as a facet of "race relations in the US, 1960-1970" rather than a standalone event.

Are you saying we had systems for spreading rummors that were just as efficient and sophisticated as today's, 40 years ago?

I'm not sure I have the right words to explain what kind of environment I mean. A platform such as twitter is a directed graph with billions of connections, all operating instantly. Tweeting is effortless, retweeting even more so. For many people this means sending something to thousands (sometimes millions) of others to see needs less than a couple of seconds of effort.

My claim is that the radical increase in efficiency and volume comes with radically new problems of scale.

I'm saying that it was easy to get a rumor seen by thousands of people if you wanted to (just tape a poster to a local utility pole), and the slightly lower startup costs in a social media world don't seem to be producing any radically new problems. This makes intuitive sense; any rumor exciting enough to provoke a real problem is gonna be exciting enough that people are willing to make flyers for it. There are certainly things I see on social media that I don't like, but none of them seem like they fundamentally couldn't have happened without social media.

Ok, you made some excellent points.