Could be because African teams are more likely to employ coaches from other nationalities? Here in Asia(southeast and middle East, China), I have seen that there is a preference to employ foreign coaches (from Europe mostly) because it is thought that they have better game knowledge and experience. Maybe FAs in Africa have a similar thought process

Edit : I misunderstood the comment i was replying to. That was comment was about the number of times African Cup has been held. As leclerc would say - I am stupid