The dumbing down of America coincided with the spread of the audio virus people came to know as Rush Limbaugh. I shall not recount his generally misanthropic philosophy or cite specific instances of his hate-filled rants.
Instead, I want to quote the late Carl Sagan and what he foresaw: “I have a foreboding of an America in my children’s or grandchildren’s time - when the United States is a service and information economy; when nearly all the key manufacturing industries have slipped away to other countries; when awesome technological powers are in the hands of a very few, and no one representing the public interest can even grasp the issues; when the people have lost the ability to set their own agendas or knowledgeably question those in authority; when clutching our crystals and nervously consulting our horoscopes, our critical faculties in decline, unable to distinguish between what feels good and what’s true, we slide, almost without noticing, back into superstition and darkness. The dumbing down of America is most evident in the slow decay of substantive content in the enormously influential media, the 30-second sound bites (now down to 10 seconds or less), lowest common denominator programming, credulous presentations on pseudoscience and superstition, but especially a kind of celebration of ignorance.” - Carl Sagan, 1995.
The only thing I would add is Limbaugh bore a strange resemblance to D.C. Stephenson, the one-time head of the KKK in Indiana who lost power after he was convicted of homicide of an Indianapolis woman.