But they haven't been without controversy.
Americans enjoy a right to free speech, and some public figures really exercise that right. The Constitution might not protect them the way they think it does, though.
The relationship between advocacy organisations based in Western capitals and their marketed constituency of marginalised and disadvantaged African groups is tenuous. What then, is the goal?
Just because they are famous doesn't mean they know what they are talking about.
Celebrities help make causes known to larger audiences and can be effective in obtaining pledges from policymakers. Yet their simplified advocacy messages can lead to ineffective or harmful policies.