Tom, if you want to lay those deaths at the door of an economic system instead of dictatorships, then honesty requires an accounting of the deaths under freemarket capitalism as well.
Although numbers of Native Americans killed by American settlers and the US Army in the 18th and 19th centuries doesn't hold a candle to the numbers killed under Stalin and Pol Pot and Mao, measured in terms of the percentage of complete destruction of a people and their culture, the US can be legitimately labelled a more successful genocidist than any dictator under the economic system of Communism. By your logic, the blame for genocide against Native Americans should be laid at the door of freemarket capitalism.
Should it be? As you argue, somewhat vaguely, that the general characteristics of Communism lead directly to oppression and genocide, I can identify a specific feature of freemarket capitalism as the driving force behind genocide against Native Americans: Private property. You know, the land that the Native Americans had the poor judgment to be living upon when Americans coveted it. Is there a similar specific principle of Communism that you can identify as the ideological basis for Communist genocide?
Speaking of private property, no discussion of genocide is complete without touching upon genocide's first cousin, slavery. Communist dictatorships virtually enslaved millions of their citizens; Americans literally enslaved millions of Africans by simply declaring them to be private property. Every evil consequence of slavery flowed from that bedrock principle of freemarket capitalism.
I stand by what I said:
When you can marshal the same crushing weight of concrete and objectively tested evidence for your opinion of collectivism as is available for evolution, then we can talk.
Offering anecdotal assertions like "100 years if failure, 100 million dead." doesn't rise to the level of evidence. You throw out statistics like that hoping that the uncritical will assume the connection you want to make, but you fail to actually make the connection in concrete terms. Show me the cause-and-effect. Slavery and genocide are consistent with the theory of freemarket capitalism; please identify the theoretical elements of communism that directly support genocide and true slavery.