How much did our thinking capabilities as a society shrink due to CIA propaganda?

What do you think, approximately? It's a genuine question because when Western news say that North Korea is the most comically secluded place where no one can enter nor leave, but at the same time obvious CIA organisations such as NK News and other Western propaganda sources know every single bad thing about North Korea. Don't people start thinking about how that is possible? If it's really that secluded and that mysterious, and that cage-like, that prison-like, I mean, for people to believe those things, our brains and thinking capabilities must have reached a certain low. What do you think? The low is approximately, for instance, in a time span. Just select any time span and guess the approximate degree to which our thinking capabilities have decreased.