Creationists agree. As I've pointed out earlier, the Institute for Creation Research has this article posted at their website:
Darwin's Influence on Ruthless Laissez Faire Capitalism.
The article's (rather leftish) abstract says this:
A review of the writings of several leading "robber baron" capitalists shows that many of them were influenced by the Darwinian view that the strong eventually will overcome the weak. Their faith in Darwinism helped them to justify this view as morally right and completely natural. As a result, they thought that their ruthless (and often unethical or even illegal) business practices were justified by science, and that Darwinistic concepts and conclusions were an inevitable part of the "unfolding of history," and for this reason were justified.
I's rather difficult to see how Darwin can be blamed for both capitalism and communism at the same time. The answer is simple: Darwin's work is incompatible with communism. Slam dunk.
And Darwin's work is also incompatible with capitalism -- to the extent that capitalism involves a system of voluntary cooperation, which goes entirely out of the schema of "natural" behavior. Which even Marx acknowledges: Marx thinks that cooperation subverts and distorts the natural interests of the human person, and that if there are any "battles to be won," they are to be won -- as Darwin suggests -- through "the war of all against all." That is, by means of conflict.
What a happy worldview!