The only thing special about them is those are the strains that men chose to cultivate. There's grass in Africa, my dude (sorghum for instance).

Those aren't just grasses. Those cash crops have very high protein content. That's critical for development in feeding nutritious food to a society. High carbs, but unreliable protein doesn't help a civilization develop.

Ultimately your reasoning here is backwards; Africans didn't develop an agricultural society of any significance so therefore the conditions must have been "hard mode" (they weren't).

No, you're choosing to go backwards for no reason. Farming in Africa has always been hard, even when the Boers, French, British, Romans, and Greeks were doing it. There's obvious reasons for that, most of them geological, climatological, and ecological.

Any inconsistent fact, like that they continue to fail at farming by rejecting good farming practices, throws it into doubt.

Collectivized farming is always pretty bad and does this kind of shit regularly. It's why there are farmer protests in Europe right now.

A yearly $4 billion loss of minerals

Minerals aren't relevant to this discussion.