Most of the "thought leaders" of the time (early 1900s) believed in racism (anti-jew, anti-german, anti-japanese etc), eugenics, population control, and killing disabled kids. Amongst other things like trying social re-engineering.

Now the thought leaders support abortion, especially if your kid has Down Syndrome. And probably the secret world leaders still support eugenics and depopulation.

Basically, they had a lot of wrong ideas then, and people still have wrong ideas now.