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.
Im immune to propaganda
If someone tried to show me propaganda, I would simply say, "No thanks."
People on this site literally do exactly this every day. Do you believe people in the DPRK get out and push trains?