I penned this two years or so ago but it's never been more relevant. I agree with this Wall Street Journal editor in this piece
This cross-referential and interactive arrangement, in theory, should allow for some resolution to divisive issues, with the market sorting out the vagaries of individual analysis. Not in practice. The Internet is very good at connecting and isolating people who are in agreement, not so good at engaging those who aren't. The petty interpolitical feuding mainly points out that someone is a liar or an idiot or both.
All one need do to test this assertion is show up on an opposing political blog and post a point counter to the group view. Target practice will ensue. Outsiders will be shot on sight and banned. Sure they'll call it incivility to justify it but this is a smokescreen. Once the posts are erased no will will know what was said and the corpse will continue to be burned in effigy by the partisan blog triumphalists and the arrogant blog owners. This method is as old as the Republic and then some. Only the technology has changed.