Propaganda doesn't totally rob people of agency free will (more accurate term), if it did this site wouldn't exist. People do have the capacity to develop critical thinking, skepticism, and a basic curiosity about the world that allow them to develop some resistance to propaganda.
You can hold people accountable for failing to even attempt to do this.
And larger point about of "they arrive at weird conclusions": oligarchs create information noise of "pick your own pet theory, any theory" except communist one. If all you ever heard of communism is usa history books, would you look at what those weird communist are saying in videos with low production values and 10 k views, instead of brightly lit studios with conventionally attractive hosts?
And even here if you decide to look at it, how likely are you to drop into some sorts of sectarian infighting with finger pointing