George's Connectivism blog is rejecting my comment, so...
Re: Centering Agents
You write, "Now, if I'm so inclined, I can listen only to perspectives of my own political party. If I follow Rush Limbaugh or Daily Kos, I can receive a constant message that assures me that I am right, and the other side is wrong. I think this is dangerous."
I reply, "Then don't do it. Read from a wide range of sources."
But, of course, you didn't mean yourself. You are concerned about what happens if *other* people don't read... well, what? Don't read things *you* think they should read?
I don't think you can make the call.
Moreover, I don't think it would be the right call to make. The net depends on autonomy - and if some people elect to withdraw from some part of the conversation, that's their right, and that's what needs to happen.