The flip side of that is that propaganda is used because it's proven to work. Yes, we should encourage everyone to individually think critically and be alert for propaganda. But I don't think blaming individuals for falling for a concerted effort to hijack their brains is helpful.
I find the argument you're making uncomfortably close to the ones conservatives use to argue against social safety nets and to avoid discussing systematic reform: namely that people need to take responsibility for their success or failure, and that if someone doesn't succeed its solely due to individual failings.
In both cases, the idea is that it's more helpful to address the negative systematic forces than just to blame individuals for falling victim to those forces.