Someone needs to update Herman's propaganda model to include how social media works.

The filters are the same, of course.

But the balance of power has shifted. eg Aggregators are now much more powerful than Advertisers.

The update should also reflect how Twitter (for example) is now exploited to shape narratives. There's always been astroturf, but now it's much more effective. What Phillip Howard (Lie Machines) calls "computational propaganda".