By providing members of the general public with quality news aggregation and community management tools, Reddit has thrown a wrench into the gears of public relations, which today still resembles the model Edward Bernays outlined back in the 1920s. (Aside: I highly recommend "Crystallizing Public Opinion" for anyone who cares about PR. It is sill relevant after 90 years.) For decades there was a gaping chasm between the general public and public figures, their representatives, and little need to revolutionize the field. Today that chasm isn't closing gradually; it's collapsing with enormous force. The bubble is bursting.
On Reddit, it just doesn't matter how much money you have or how much you've invested in the community or how much perceived legitimacy you have outside Reddit; anytime you make a comment, you're throwing yourself to the lions. Lions who upvote the most caustic, brutal, and incisive questions they can come up with, focusing the community's attention and demanding more of public figures in a way no one could have predicted in 1995 or even 2005.
Do you know what happens when you type "reddit new york times" into Google? The top result is /r/nytimes. As a subreddit, it is essentially dead. Do you think it would be dead if the New York Times did not have its own user-generated commenting system? Do you think the New York Times would like to remain in control of its own user-generated commenting system? Of course it would. The point I'm arguing is that Reddit, by its very nature, has helped push the New York Times to adopt a policy of accepting user comments, and many other news sources have followed suit. Of course this point is impossible to prove, but even if there is merely a grain of truth to it, the implications are that those who own the news business are no longer living in a unidirectional media world.
The larger argument is that Reddit (and its predecessors such as Slashdot and Digg of course; I've unfortunately unintentionally marginalized their role in this comment), by its very nature, has systematically and irrevocably altered the public's expectations for online participation and engagement. There is much more going on here than textbook case studies.