It isn't so much that people lack skills or knowledge of things at the individual level. It's that the body of knowledge, including its distribution and reproduction, serves the interests of the bourgeoisie in reifying capitalism upon the level of the individual. The way the news is made, how movies are made, etc is a capitalist way of doing things, and reinforces a capitalist thinking of why the world works.

You likely did not come into a socialist consciousness out of your innate cleverness and capacity for understanding, you came to such a consciousness because new information undermined the system of thought which had been trained into you since you were a child. In theory, I don't know you.

"Why is propaganda so effective," well, why do you think the way you do? Our thoughts and beliefs are much more malleable than liberalism would like us to believe, for example. Pretty much anyone can be brought to any kind of understanding. Entire societies can be brought on board with genocide, as we see now. You can levy this as an individual moral failing at the scale of a whole society, or we can look at the systems of the production of information for what they are and see that control over thought and culture is actually very material. With this in mind, we can understand that the social zeitgeist may follow the agenda of those who control the levers of culture, and develop our own means of doing so as a counter.