Capitalism has killed countless people and continues to do so today in places like the USA, China, and Russia as well as around the world. Greed and wealth disparity is a disease ever-present.

Okay. Good so far.

Historically, plutocracy was the cause and justification for many horrible atrocities including the Atlantic Slave Trade and the Opium Wars.

Incorrect. It was settler colonialism and imperialism that directly drove both of these atrocities and then some.

I've personally never met a Liberal who defended any of those things

It doesn't matter. Liberalism is the ideology of capitalism, which also whitewashes crimes committed by the US. And there are plenty of liberals who would happily put people like me back in chains for not voting for their "harm reduction" candidate.

You know what I would never do, though? Compare communism/socialism to whatever the fuck the Chinese Autocracy is. That's just delusional.