It's a million improvements in a million individual situations. It's public programs to raise health and educate people made feasible by economic growth. It's happened in countries with vastly different systems in very different parts of the world for the last century.

The biggest reason for reduction in extreme poverty over the last decades is the responsibility of the Chinese state. The fastest drop in family size ever was overseen by the totalitarian Iranian government.

Beware easy one line explanations.