In the US, social media has been captured by propaganda not because an authoritarian government has made it so through law and violence, but because the consumers like the propaganda.

The current situation is the result of free speech and consumers being able to choose the kind of content that they enjoy.

It is hard for me to avoid the conclusion that your argument in effect logically implies that free speech should be further curtailed and that elites (but the Right Elites) should be in control of the sources of content.

Which is a defensible position to take, actually. But people generally don't take it because reduction in free speech and consumer choice is anti-democratic. So the essence of this position is actually that we have too much democracy, not too little.