The aforelinked Julian Sanchez post merits further discussion. You should read the post, as it is very dense and provocative. Here is the conclusion:
So here’s a hypothesis: Epistemic closure is (in part) an attempt to compensate for the collapse of geographic closure. A function no longer effectively served by geographic segregation—because the digital equivalents of your local hangout are open to invasion by the hordes from New York and London—is being passed to media segregation, bolstered by the sudden demand that what was once tacit and given be explicitly defended.
I actually think that the interpersonal dynamics that Julian describes are extremely influential. In New York and Washington, D.C., many young left-of-center writers and activists come from parts of the country where their political and cultural sensibilities placed them firmly in the minority, particularly during the all-important adolescent years.
Given the rise of communications technologies that Julian references, many were able to gain exposure to and to identify with communities located elsewhere that affirmed their political and cultural sensibilities as praiseworthy, and indeed as a mark of superior intelligence and virtue. The same can be said, of course, for young right-of-center writers and activists, though my sense is that the left draws more heavily on “cultural defectors” than the right. In many respects, these cultural defectors set the tone for the left.
And this tone is often contemptuous — it reflects long-buried resentments formed in towns and cities long since left behind. If the kid who stuffed you in a locker was an ostentatiously devout Confederate-flag-waving right-winger, anger at the injury will stay with you, and will likely be transposed onto all conservative politicians with southern accents. What’s interesting is that the technological death-of-distance means that the locker-stuffed youth can react in real time, sharing news of the incident with like-minded students at neighboring schools and beyond. Rather than feel humiliated, defeated, and cowed, one is more likely to see personal rivalries and hatreds as part of a larger cosmic struggle. So while advanced communications technologies can fragment a culture, they can also facilitate the creation of new alliances and new encompassing narratives.
Julian describes this dynamic, and the reaction to it, very well.