I suspect it is more of a result of changes to the overall societal context as a whole, of which the formal education system is just one part. For instance, we

I suspect it is more of a result of changes to the overall societal context as a whole, of which the formal education system is just one part. For instance, we are certainly all much more exposed today to people ranting pure bullshit than we were in decades past. That seems likely to be part of it... seeing so many people spouting absurd nonsense, and then seeming to "win" the interaction, must normalize that behavior and encourage people to try it themselves. But I think it is not just about "knowing fewer facts" but also about "having less ability to reason about things and derive a fact (or reasonable hypothesis) for yourself, even about simple matters".