There are more mouths to feed and less territory per capita for each person (thus real estate inflation in desired locations). Like lanes on a highway, the population just fills the capacity with growth without the selective pressure of even selecting for skill or ability. The ways we've come see mostly front loaded as initially population takes time to grow while the immediate low hanging fruit of domestic drudgery being eliminated was quite a while ago. Meanwhile now "work" that has filled much of that obligation in the home has expanded to necessitating two full-time income households.