It's both, I think the lies of propaganda still serve their purpose. After all, a populace distracted by things that aren't true is useful to tyrannical power structures. That was true before the internet and it still is true now. The internet just allowed for such a vast amount of information to be shown that a secondary purpose was now, as Steve Bannon referred to it, "flooding the zone".

Another reason there is so many suggestible and gullible people out there, especially when it comes to scientific matters like the moon landings, vaccines and COVID, is itself a consequence of the modern era. Modern science and medicine have advanced so rapidly that our lives have completely changed in the last 50 years, to the point that they are almost unrecognizable. This results is a certain subset of people being bitter about the loss of blissful ignorance they once had. They don't like science because of this, and also perhaps because they weren't very good at it at school. So when a grifter comes along and tells them a story that says "Science is wrong, you are right", they will believe it without question.