The appropriate question shouldn't be "Why does Africa have so many languages?" but rather "Why do developed nation-states have so few?" High levels of synchro

The appropriate question shouldn't be "Why does Africa have so many languages?" but rather "Why do developed nation-states have so few?" High levels of synchronic linguistic diversity should be considered the pre-modern norm, even aside from the usual troubles of distinguishing languages from dialects. And nation-states are very common these days. The answer is probably mostly language standardization, promotion of elite lects, network effects, and official promotion of the standard language, often alongside the abuse of minority language communities.