Why are the blogs and "netroots" so radically to the left of the mainstream left?

While I am a Democrat, I am distrubed by the level of radicalism on the internet. These blogs, like the Kos and the HuffPo are FAR to the left of anyone in the mainstream of the party. It bothers me. I want a clear eyed party, not some ultra PC socialist hateful people who gleam over Obama because they hate the Clintons. Why are the netroots so far to the left of the mainstream Democrats?