And this is the primary conceit and lie of postmodernism, and why in suggesting to us a greater enlightenment it just leads us back to stupidity, with few if any redeeming qualities (at least few that couldn't fit on a post-it note, like "check your assumptions").

Because it's a complete fallacy that if only we had known what Walter Cronkite had for breakfast that he only researched his stories as well as had a random TikTok influencer whose breakfast we also know about. Good journalists actually do impressive work. I'm not going to go talk to dozens of eyewitnesses and call up multiple government offices, taking special care to vet the more extraordinary claims by finding multiple independent sources who corroborate it. No! I'm going to find some shaky cell phone video that shows a quarter of what is needed to conclude anything, extrapolate wildly about something that looks bad on it, and scream at everyone to retweet. That this rubbish is the same as careful journalism is exactly the postmodern fallacy.

At the very same time, modernism was coming to grips with fallability. Analytic philosophers were delving into the philosophy of science, helping to some extent set limits on what we could know. Scientists were refining ideas of statistics and approximate models. We were developing the tools and mindsets necessary to cope with the idea that some information is more reliable and some less, and that we can make tentative progress even in the face of substantial uncertainty.

But the postmodern approach was (at least epistemologically) indistiguishable from saying, "You know what? This isn't perfect. It's not absolutely blindingly brilliantly perfect, so it's trash. Forget it all." Postmodernists met Descartes' demon, decided it was in each of us and could not be bested, and consoled themselves by writing incomprehensible prose that we were supposed to think was terribly profound but mostly was just laying the foundation for ongoing confusion and misapprehension.

So I agree, largely, with your description of how things have turned out historically, but not that there's any necessity there, or really much of any accuracy. We got clever, pointed the cleverness at ourselves, and too many of us folded under the emotional strain.