See "The Black Book of Communism".
"Already famous throughout Europe, this international bestseller plumbs recently opened archives in the former Soviet bloc to reveal the actual, practical accomplishments of Communism around the world: terror, torture, famine, mass deportations, and massacres. Astonishing in the sheer detail it amasses, the book is the first comprehensive attempt to catalogue and analyze the crimes of Communism over seventy years. [...] As the death toll mounts—as many as 25 million in the former Soviet Union, 65 million in China, 1.7 million in Cambodia, and on and on—the authors systematically show how and why, wherever the millenarian ideology of Communism was established, it quickly led to crime, terror, and repression. An extraordinary accounting, this book amply documents the unparalleled position and significance of Communism in the hierarchy of violence that is the history of the twentieth century."
That said, this is almost too obvious to point out, but it happens to be true that the Soviet Union and Communist China (and Vietnam, Cambodia, etcetera) murdered 100 million+ in the name of "building socialism", and it is quite possible that the original poster knows people from those countries who lost loved ones to socialism/communism.
Seen in this light, I'm not saying that OP's phrasing was the way to go, but it's understandable that there are people frustrated by this all too common style of ignorance. It's not idealistic to actually support socialism in 2011, it's simply ignorant.
At the risk of reductio ad Hitlerum, certainly an offhand comment in favor of "rational, libertarian Nazism" would have dominated response to the essay, yet we find it acceptable for educated people to make offhand complimentary references to a polar opposite ideology that actually killed many more people.
 Or in this case, direct rather than offhand
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