Has the US fallen much in education quality in absolute terms? Or just relative to other countries? And how does that map relative to the percentage of the population being educated at that level?

A world where underperforming people are just pushed out of the path of ever attending high school or college, like some of my friends's parents were, may lead to higher statistical education outcomes for high school education while still being worse for the country at large than having those students attend high school even if they don't make amazing grades.

You bring up "the replacement of newspapers that invite critical thinking by yellow journalism" as if the term Yellow Journalism wasn't literally used to critique one of the major US newspapers over a century ago. Sensationalism and rabblerousing is, if anything, the normal state of news dating back centuries!