I can't speak for african animation, but I know a lot of Irish animation studios and artists are more independent. Because they are telling stories and making art that are more culturally detailed and relevant to the Irish audience, but would not be understood by the masses (especially Americans). So if they wanted to work with Disney they would have to dilute and remove much of that. And that would be a real shame!
So I imagine it might be similar for many African artists. They are not making work designed to appeal to Westerners, and they don't want to. They just want to make their own, more niche thing.