European colonialism did not lead to stable African nations, in large part because the borders did not reflect local tribal identity. In addition, during the pre-independence period they brought numbers of future African leaders to school in Europe, where they learned Marxist nonsense. BUT, the idea that Africa would be better off in the primitive brutal barbaric societies that prevailed before the colonial period is ludicrous.
How do you know that? First, Europeans killed millions of Africans in the process of conquering the continent. Second, Africa may well have developed organically if left alone, possibly by borrowing what works in Western civilization. For all we know the people would be much better off now if the European conquest hadn't happened.