You're correct that the reality is much more complex. To expand, I would say that people are indeed susceptible to propaganda, but only propaganda of a certain kind. It has to reinforce their preexisting biases. You can't just force any propaganda on any arbitrary person, that's not going to work. That's why I say people do it to themselves. They come to trust the public figures who tell them specifically what they specifically want to hear, and then this trust and good feeling can be exploited for other purposes.
That's not unique to any one political party. All political partisans are susceptible to propaganda, but only party-specific propaganda. There are different forms of propaganda on different sides that would never work on the other side.
However, if people are put in a situation where the only information they have access to—or the only information given an official sanction—is the propaganda, then whether or not it conflicts with their existing biases, they're pretty unlikely to be able to refute it. Especially not over a long period of time.
Also worth noting that saying people "do it to themselves" only applies to adults: the adults who are "doing it to themselves" are, in fact, doing exactly what I described above to their children: providing an "official sanction" to only the propaganda that agrees with their biases, thus ensuring that their children grow up molded in the same way, with no easy way to make an informed choice for themselves.
> the adults who are "doing it to themselves" are, in fact, doing exactly what I described above to their children
To an extent, yes. However, there are a number of mitigating factors. (1) Individual parents vary widely in their persuasive skill. (2) If there are 2 parents, those 2 don't necessarily agree in their beliefs, which means mixed messages for the children. (3) The child's friends, neighbors, schools, and community are also important influences on the child. (4) Genetics guarantees individual differences regardless. (5) Kids have a natural tendency to rebel against their parents, regardless of the parent's beliefs.
A lot of kids turn out a lot like their parents. And a lot of kids don't. Some even become the opposite of their parents. So the parental influence is definitely a factor, but it's not inescapable.
In any case, most kids pay very little attention to politics or "hard news" before they reach voting age (or even after). The news consumption itself tends to occur mainly in adulthood.
There are many good points in this thread, which led me to this realization: kids are indeed not very interested in national politics, but they are very attuned to the social politics of their peers, which can be pretty cliquish, isolating and devisive.
The propaganda that we are concerned with here deliberately seeks to trigger these childish responses in adults. If you go around telling people that they are entitled to something which these other people are taking from them, you will get some disciples regardless of whether there is any merit to the claim. It is like a mountainside in snow: you will get many small avalanches, but now and again a big one will let loose and sweep everything away.
That's not unique to any one political party. All political partisans are susceptible to propaganda, but only party-specific propaganda. There are different forms of propaganda on different sides that would never work on the other side.