Perhaps "conspiracy theory" was a poor choice of words since they're not so much theories. The approach of divide and conquer had long been used in Africa to manage populations within colonies. Further, the identity cards that marked large "H" and "T"'s to denote Hutu's and Tutsi's were both used and encouraged despite intermarriage between the two groups being "frequent" as documented by the UNHCR (http://www.unhcr.org/refworld/topic,463af2212,469f2d0c2,3df4...)
I note further that it is no secret that French colonies have significantly lower economic growth than their British counterparts: http://faculty-staff.ou.edu/G/Robin.M.Grier-1/religion.pdf (pdf). Africa in general has faced a number of difficulties - but even within Africa there are some much better examples of governance than others and in almost each (if not all) of those cases, those examples were not French colonies (there's a TED presentation by Hans Rosling if I recall, that speaks to economic growth/poverty in Africa)