A publication's "editorial voice", ranging from grammar and typography, to selection and discussion philosophy, are significant. There's a reason we see things as "New York Times" or "Fox News" or "Mad Magazine" or "Cosmo" or "The Economist" or "Soldier of Fortune" in voice or tone.
This is harder to pin down with blogs and social media, though distinctions can emerge, whether through self-selection, path-dependency, gross scale, algorithms, or some combination of the set.
Prejudice can be misused, but its advantage (to the judger) is that it makes judgement cheaper by reducing the set of what needs to be considered, at least for an initial judgement.
That's characteristic of any domain in which there's an information overload, or in which distinctions are subtle and difficult to identify initially. And argument, by the way, for dealing with copious information less by enhanced processing and more by expedited (and cheap!) discarding heuristics.