Chait observes that "the world of popular culture increasingly reflects a shared reality in which the Republican Party is either absent or anathema":
Liberals like to believe that our strength derives solely from the natural concordance of the people, that we represent what most Americans believe, or would believe if not for the distorting rightward pull of Fox News and the Koch brothers and the rest. Conservatives surely do benefit from these outposts of power, and most would rather indulge their own populist fantasies than admit it. But they do have a point about one thing: We liberals owe not a small measure of our success to the propaganda campaign of a tiny, disproportionately influential cultural elite.
A media effect that occurs over a long period of time and interacts with social influences and other inputs is extremely difficult to tease out with the tools social science researchers have available to them. That isn't to say communication researchers aren't always trying; for instance, there's a long line of research on what's called "cultivation," which says that over time television in particular shapes our view of how the world works. It isn't without its critics, but few doubt the basic premise that what we watch can influence what we think.
Alyssa's push back:
[Chait] ignores one of the strangest disjuncts between Hollywood’s stated and practiced values, and one the deepest drivers of the shallowness of Hollywood liberalism: the striking illiberalism of the industry’s hiring practices. The Hollywood liberals who shape the worldviews Chait discusses are largely white men, and the actual patterns of employment in the industry are the kind of nightmare stories liberals like to tell about what American life would look like under conservative rule.