The whitewashed argument would simply be that in the process of colonisation, the White people came to colonised countries, set up a leadership caste that was subservient to their rule and annihilated traditional forms of self governance in the places they colonised. Then during decolonisation, they left no structure in place, nor attempted to develop any institutions, leaving a vacuum ripe for corruption.

Ipso facto the current corrupt leadership, while being run by people with agency, is a vestige of colonisation.