In most cases only very few have enough time and willingness to analyze news enough to spot non-hyper-evident propaganda, make links between news/depicted facts to form a personal view etc. Having created a fast and entertained and nervous/emotional society do the trick for most.
The secondary aspect is that human life do have a limited timespan, actual rulers know a day they'll die as anyone else, so their target is not master the masses at infinitum but train "new people", some "the masses", will be trained, are already trained, to be like Chinese commoners, Ford-mode stereotypical workers, or ancient Greek "useful idiots" (not an insult, there is really a such concept in classic Greeks, ῐ̓δῐώτης to be more precise), or in practical terms obeisant workers that do whatever they are told to do with the best effort, they talk about whatever they are told to etc. Take a look at comments under most news websites: on usenet users decide topics, now with limited and contained exceptions like HN or Reddit on most platform people talk following a plot. Take a look ad Japanese/Asian TV show with the small rectangle to suggest the listener how to react to what it listen etc.
Very few will be pushed to think about propaganda and ultimately embrace it, since seeing it's effects is hardly imaginable/utopia a really free society where no one try to betray others.
Those cohorts will be the "new man" built by the actual rulers, new élites, new "middle class", ... shaped as they imaging the society.