The Malinese empire and the following Songhai empire would beg to differ.
Where are the great monuments and buildings? Where are the great works of art and literature? Where is there even evidence of a written language?
I fail to see those on the list of "First world" nations...
You can't argue in two opposing directions...
A competent independent and thriving culture exists, advanced Europeans arrive, destroy it and then leave... or are forced to leave, and all signs of self-sufficiency vanish.
And A primitive hand to mouth culture exists, Europeans arrive, introduce modernity to the culture, are then asked to leave or are forced to leave, and things degenerate into the original primitiveness.
Both are blamed on the Europeans.