On the surface social media looks completely benign, but they have these far reaching insidious impacts. Our elected representatives don't even have a basic understanding of how these sites operate... yet you have the majority of the population being fed content by these algorithms that determine what you see when, and they're completely opaque. They've got scores of analysts and psychologists shaping this stuff full-time... no single entity in human history has had this level of data and reach into human behavior, and it's all proprietary.
Small intentional changes over time to such wide-reaching algorithms can literally shape humanity in ways that may be entirely impossible for an outsider to detect.