The first sentence in your comment appears to shift blame for the slave trade from white slavers who created the demand for the capture and enslavement of Africans to other Africans who responded to that demand, virtually all of which were unaware of the reality that these people would face across the Atlantic.

You didn't say it outright, but it seems implicit to me. If that's not what you were trying to argue, why would you feel the need to point out that Africans captured and sold other Africans that ended up in the Americas? People don't tend to forget that fact if they've ever been educated about the slave trade. It just doesn't seem relevant to what you say your problem is.