Accountable how?
I mean, did we ever hold Genghis Khan accountable?
History is littered with the victor and the defeated and the legacy they leave. It's not specific to Africa. Which isn't to say I am wholly against things like affirmative action in the US. But no matter what anyone does, you're never going to undo the past.
Generations of people get f'ed over by the rest of humanity and there's really no recourse in nearly all cases. Which leaves a little of debate to a cute thought exercise, but nothing that provides much more value than a contest over victimhood.
Just like Germany still pays for what they did to the unfortunate Jews, countries like Spain, Portugal, France, England and Italy can do the same for their misadventures in Africa.
It doesn't undo the past, but assists those places to recover. Even a simple open apology is a start, something that heals their wounds. It's like Europe keeps pressuring places like Turkey to admit to Genocide against the Armenians.
Only Africans can help Africans lift themselves out of the hole that they're in, but things like these help.
Also, attitudes like Zachs, which is no different than saying "that homeless guy should get a job, that silly bumb", are not helpful either.
Racist white supremacist attitudes like Zachs are effectively saying, if you read between the lines, that "see these violent savages can't rule for themselves, we should run their countries for them"