Note that I'm considering the triangular trade as a form of colonization; even if it didn't involve proconsuls, it involved an external actor explicitly fomenting a hierarchical and extractive social order.

If you redefine colonization, you can get the results you wish.

Note that here homunq's stipulation actually makes his claim more false. After all the parts of Africa benefiting from the triangle trade were some of the richest and most well off parts of Africa (not for the Africans being sold obviously) before colonization proper started.

I'm not interested in proving colonialism was always economically inefficient, just in pointing out that OP's aside was troubling. That said, your appeal to consistency isn't correct, it overlooks all nuance. Colonialism has clear and unambiguous ties to the problems that exist in Africa today, but it has no such ties to the successes in South Korea or Taiwan.