This doesn’t make any sense. We have more access to entertainment, be it comics, porn, or films, than any period in history, yet we continue to make more substantial scientific progress than any point in history.
Scientific progress is typically the result of outliers at the upper end of the normal distribution which doesn't inherently contradict a decrease in average knowledge. (i.e. a larger standard deviation could overcome a lower average)
Consider nutrition. Technological advancements mean that people have access to both higher-quality food and lower-quality food than their ancestors. In practice that seems to have resulted in some people eating healthier than their ancestors could have, and others worse.
Consider nutrition. Technological advancements mean that people have access to both higher-quality food and lower-quality food than their ancestors. In practice that seems to have resulted in some people eating healthier than their ancestors could have, and others worse.