You're running so very far to the other extreme to make some vague defense of communism.
No communist leader of that era rose to power without the help of the people of that nation. Chairman Mao gain the support of the farmers who were stuck in poverty and were being exploited by the foreign business interests of the time.
This was one reason why the communist revolts in Europe, Russia, and China occurred at all - it was because they found communism as a way to throw off the capitalist tyrannies that kept them downtrodden.
To be fair, neither extreme is very beneficial for the good of all. Also, just because there have been communist dictators people shouldn't ignore the good that social democracy has done for the world despite the two terms being mistaken for one another.
Also, we need to legalize recreational drugs and prostitution.
Ideas don't kill people, people kill people.
"After all, you know, there are worse things in life than death. I mean, if you've ever spent an evening with an insurance salesman, you know exactly what I mean."
The point you are missing when it comes to the death toll of communist ideaology is that the ideology itself is not inherently evil, nor are the people, or even it's leaders really. I agree it's a ultimately flawed idea from an economic, political and societal standpoint. But the point is this; radical and revolutionary politics tend to take a hardline stance, no matter where they are. Violence comes from the far right and the far left. The common thread it that it's adherents have crossed the line from tolerance of others views and ideas (at least to the point where they shouldn't be hurt for them), they have crossed the line to intolerance of others ideas; ideas in opposition or that are not sufficiently "revolutionary" enough are to be disposed of, in one way or another.
When radicalism gets to the point of saying, "Our ideas are so right, that it is acceptable to break some eggs to make our omelet", that's when the death toll starts to pile up. That is the danger of any type of radical/revolutionary politics. Look what seems to be happening in Norway right now.
Also, a great movie of the mob mentality of radical communist politics is the Japanese film Red Faction. Check it out.
How was Mao Communist? His government retained a stratified class system where power was centrally located with the few at the top. That alone blows it out of the category of Communist.
"If your opponent is of choleric temperament, seek to irritate him." - Sun Tzu
You are better off looking at causal relationships than correlations. For example, one could easily argue that democracy was an evil ideology in the 19th century. Nearly every democratic government conquered and exploited some group of people, in addition to genocide, slavery and racism. How would you justify the benefits of democracy to a native American or African in 1825?
There are many flaws of communism, but you need to actually need to specifically identify rather than simply over generalizing.