It's not just "Western stupidity" it is human stupidity!

The sum of the intelligence of the human race is finite. Divide finite intelligence by increasing population and the result is decreased intelligence per population member. This explains part of it. The remainder is easily explained by the principles of entropy -the natural tendency of all physical systems to tend towards disorder. The longer time goes on the more disorder results. (The first is somewhat facetious - the second a proven principle of physics)