US actually had a surprisingly high literacy rate and people were avid readers, so much so that the British used to point out they spoke as if they were writing prose and famous writers were followed around like they were super stars. Not only that but the people would attend lecture halls to listen to politicians and scientists talk for hours and hours. It’s no coincidence the founding fathers were intellectuals.

Newspapers, printed images, television and internet successively changed the depth of discourse and forms of entertainment so that communication started being less about ideas and more about visceral reactions and memes. People stopped reading, stopped paying attention (the people that would once go through snow to see politicians debate for seven hours or more stopped being able to focus) and stopped being able to process information.