I mean, are they even factual though? Africa may be less developed than the United States, in general, but most of it isn't really in the "running from wild predators like cavemen" stage either. Obviously the specific people who are descendants of slaves in America wouldn't even exist without their ancestors being kidnapped, due to having entirely different life circumstances, but it seems unlikely to me that the equivalent descendants of those people would live without civilization. Poverty, perhaps, but that isn't the same thing. And Hitler, for his part, was good at gaining public support as far as I'm aware, but I don't think a leader who almost gets his country destroyed by starting almost unwinnable wars against half the world while wasting resources on murder and in pitting bits of his government against eachother, all while amped up on drugs, can really be called effective, unless one's definition of an effective leader is just having the ability to aquire a leadership role in the first place.