The whole subject of colonial economics and such is very complex, so I'll just say that your point does sound valid, I just don't know if that alone would be enough. But one thing you did raise, how morality wasn't the main factor... so really most everyone back then were assholes when it came to different races. Which supports my point that overcoming that would take far more than a few leaders casting away their slaves, and like I said, we still have racism issues in the damn 21st century where things ought to be so much better logically.

Maybe humans just suck collectively.