> There are more people now, and all else being equal, there would likely be more stupid people as well, in absolute numbers. That might give someone the impression that things are going downhill.

Can you point to a specific observation or claim that this is relevant to? I don't see any argument that's sensitive to the absolute number of stupid people in the world. This is a non-sequitur at best.

> Also, the article and book claim that people have read less classics than some time ago. But the same argument is even worse in reverse: people from some time ago had no clue about climate change, computers, women's rights, or AI. With all their smarts, they let this happen. How does that suggest that reading the classics is useful?

Your argument here is implicitly that if reading the classics were useful, then we should've invented computers sooner than we did? Do you find that compelling?