What do you mean people used to do a lot better? As far as I know https://en.wikipedia.org/wiki/Flynn_effect was a thing until recently.

The human body is quite complex as well.

Graduating a for profit private college that is aiming to maximize profit, by churning out specific degrees does not mean you are educated. Having a college degree is not synonymous anymore with well educated.

The measure (college degree) became a target, and thus it stopped functioning as intended.