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.
I think there are certain "turning points" in a person's life where they either go down a dark road or they don't. I definitely had a point in my 20s where the far right seemed tempting but I didn't go there, it's the easy option, actually learning about the world is harder. I reserve my right to judge people who did.