re: South Africa is about to go full Zimbabwe

People also rarely mean West Africa when they discuss Africa too. They usually mean Central and Southern Africa, which were two of the more difficult regions to colonize. The places I mentioned had all the features of other civilizations. More advanced civilizations like Europeans, Chinese, MENA had some idea of otherness, and used that as a method of organization in a sort of us vs them fashion (I'm generalizing to a massive degree here). I don't know enough about the other regions of Africa to say that they didn't, but I'd wager that animistic religions and ethical philosophies probably lent themselves to diversity, and thus decentralization, which aids your original point.