Aside from tech making information more accessible, centralization and monopolization likely played the biggest part. Driven by the design of our monetary system. Most new money enters the economy backed by endless streams of real estate debt (mortgages), public debt and corporate debt... All these well-moneyed areas (real estate, government, corporations) have become monopolized and highly political. There's just no room for real knowledge work. It's all about status games and BS internal politics. People who benefit from Cantillion effects have no interest in bringing nerds into their organizations to compete against them for their spot in front of their easy money printer.
Insiders are mostly hiring people who are dumber than themselves; people whom they can control.