I'm not familiar with popular news agregator sites but wonder how good they are at vetting serious news articles? My guess would be that hard core news junkies are quite accurate in their assessments. I'd choose a small group of these people over a group of a thousand random Facebook users. Would I choose them over a group of 20,000 Facebook users? Probably.
People need to be taught how to evaluate a website not just news or other articles. When I think about my students at school I am horrified at how little they learn about how to evaluate websites. We used to use books that we could rely on and although there are plenty of books out there that are full of woo and nonsense I'd say books are way more reliable than websites. In other words evaluating a source is a rather new thing that the average person never really had to do all that much before the Internet came along.