Now it's all over the internet, a sort of radicalization-lite that starts in tighter circles where kids swap conspiracy theories and alternative perspectives, and more of this stuff quickly starts leaking mainstream.
I think any dominant culture de facto produces and consumes its own propaganda, to some extent. That's good and bad. The information age has made the system more chaotic because of the speed and convenience of data exchange, and that leads to more frequent clashing and fracturing in society, as common indoctrination does lead to greater social cohesion, across cultures. Propaganda has less of an effect and people have less reason to rally together because of different views on, say, in America's case, history and even some of our modern world building.
What, you think radicalization is unique to the chans? You'll see it's all around us if you're not unfairly exclusive in your definition of radical.