Often there exists an overlap between the group of people who have a strong financial motive not to report a story, and the group of people who provide the overwhelming majority of information regarding current events to the public. To the extent that this overlap exists, an independent voice is needed and blogs fill that gap perfectly. I assume this is what you meant by "these sites have more credibility simply because they aren't major corporate news organizations."

Beyond that though, if someone is stuck in a positive feedback loop with say, the 'John Ashcroft is the root of all evil' meme, or the Christianity memeoplex ('I am being punished by Jebus/Jebus is blessing me now') they are going to naturally be more receptive to supporting arguments in order to either strengthen the amount of positive feedback they receive from a given meme or reinforce their ability to defend it from being dislodged. Personal example - I saw an excellent paper thoroughly deconstructing and destroying the WTO-is-bad-for-non-US meme on every factual point. I had an extremely difficult time reading this paper at all simply because that meme acts as a cornerstone to many of my other political views. The experience was terribly uncomfortable and not one I'd care to repeat on an hourly basis - in fact I spent the next few hours trying to reassure myself regarding my earlier position through fact-gathering at hard-leftist blogs.

The point is, this entire phenomenon you're discussing seems like the natural extrapolation of Pavlov into the realm of memetics. Generally people take the path of least resistance/greatest pleasure specific to their situation and environment - the differences therein between people result in different belief systems that are all fundamentally based on providing pleasure, smooth environment interaction, and rationalization for the person in question. Learning the flaws in these beliefs increases pain, reveals the fundamental absurdity of existence, and induces self-recrimination for the flawed memes the individual in question has spread in the past. Many people claim to be open-minded but few are energetically attempting to prove their every belief wrong.

Also COCKS.

Fuck, I FUCKING hate talking about memes.