As I recall, much of the worst and most extensive use of slavery throughout the last 500 years was under the watch and encouragement of those western global powerhouses.
- Between 1526 and 1867, about 12.5 million Africans were shipped out of Africa in the transatlantic slave trade, with over 10.7 million delivered alive to the Americas. Most enslaved Africans went to the Caribbean and South America; only around 6% went directly to British North America (what became the U.S.).
The US wasn't even a country for most of that period.
And as far as the "colonial influence" in the areas of the "majority participants", that would be the Spanish and Portuguese. But we're not going to browbeat the descendants of the Spanish people are we...for reasons.
The objections a lot of people have to the nature of the discussion isn't the fact that slavery is evil, or is a shameful part of US history.
The objections stem from the notion that it's something "uniquely American".
When, in fact, it was an unfortunate "global norm", and one that we actually participated less in than other empires. Yet, it gets portrayed as being some sort of "enlightened" position to rip on America for it.
The Brits and us spearheaded ending that evil global norm.
And while the Brits started the process to eliminate it about 20 years earlier, they took a more "don't ruffle any feathers" approach (they did a phased rollout, paid direct compensation to the slave owners, and exempted the East India Company)... we fought one of the bloodiest battles in history to put an end to it.
Yet, in all of the contemporary conversations about the subject, the USA is singled out as if they're the sole "bad guys" in the whole affair.
That's what people object to (and thereby, try to overcorrect for)
If the whole class is complicit in stealing the answer sheet from the teacher's desk to cheat on a test, and one student gets a guilty conscience and fesses up and tries to make it right, it's quite frankly not fair to hyper-fixate on that one student's role in the initial "sin".