The point, is Afrocentrics like to lay all the ills of modern Africa at the feet of colonial Europeans, when in truth, Europeans were able to colonize the places they did because so many of those ills were already in effect. Sub Saharan Africa was merly one of the more extreme examples, though Polynesia does jump out in my mind as being more so, but ultimately for the same reasons of geographic isolation and lack of trade with the wider world.
You saying the disparity was only because of the industrial revolution ignores that the particular set of social conditions existant in Europe, and in particular Britain, at the time allowed the industrial revolution to happen there and not somewhere else.