Or that many of the independent movements were sponsored by the eastern bloc. To take Zimbabwe as as example, the only plausible successors to white Rhodesian rule were Joshua Nkomo (backed by the USSR ) and Mugabe (backed by communist China). Not the best recipe for a fledgling democracy.
The fact that so many of the former colonial nations were transformed into Cold War battlegrounds by what you can argue were the new imperial powers in the world was probably the last straw for a lot of those countries.