The risks that come with the filtering of information are a returning theme on this blog. In my post The Spirits that We Called I argued that the right filtering of information is crucial because people don't make a lot of effort questioning the order or relevance of information. If it doesn't come "cheaply," in the sense of it not requiring time and effort, it's likely to have low impact, thus the importance of search engines and social networks for democracy. From an evolutionary perspective the limiting of time spent on information gathering is just a careful dealing with resources and not irrational at all. That has always been the case, but the internet vastly centralizes provision of information and amplifies its impact at the same time. The consequence to draw, as I argued in my post Can Technology make us happy?, is that we should be very careful with designing information structure and filters. Do we really get the information that we need? One of the biggest problems, I think, is The Illusion of Knowledge that leads people to believe they have all the relevant information already.
Some days ago I saw the below TED talk by Eli Pariser, who makes this point extremely well. If you have ten minutes of time, they are well spend on the below video.