If they hadn't been coincidentally liberated as a result of the south losing the Civil War they would have died as slaves as did most slaves in the history of the American south.
I think you're totally wrong.
Talking about benefitting from skills is a type of right wing propaganda to soften the utter brutality of slavery. Along the same lines as the kind of garbage taught in the past such as many of them were happy to be slaves. They don't want white kids to feel bad. That's not teaching history. They have said as much and that is stupid. That's right wing INDOCTRINATION.
BTW, on a personal note I have lived in the deep American south. As I do have white skin, I have wondered if modern black people wonder or even assume that my ancestors were slave masters. It's not a pleasant feeling, but I wouldn't blame them if they did. When I visited Germany as a teen I had a hard look at every older German and ... wondered.