There's a fascinating piece in Vanity Fair about politico.com by Michael Wolff. Here's the thesis:

In the fourth issue of Wired magazine, in the fall of 1993, just as the Internet was entering public consciousness, Michael Crichton, the author of The Andromeda Strain and Jurassic Park,
wrote an essay arguing that newspapers were doomed because they were
too dumb. As information became cheaper, more plentiful, and easier to
get, consumers, he argued, would become ever more immersed in their
specific interests and understand that their more generally oriented
paper—at least in the matter of a reader’s special interest, but also
by inference everything else—had no idea what it was talking about.

Sixteen years later, the ultimate result of Crichton’s theory about
the fallacy of general-interest news—and, as a corollary, the answer to
the riddle of who’s going to report the news when traditional,
general-interest news organizations stop doing it—is, for better and
worse, Politico.

...CNN changed the nature of politics and political reporting by
compressing the time it took for something to happen, for it to become
widely known, and for newsmakers and the public to react to it (i.e.,
the news cycle) to half a day—whereas the newspaper news cycle, from
next-day publication to day-after reaction, was 48 hours, and network
television’s news cycle, from one day’s evening news to the next day’s
evening news, was 24 hours. Politico brings the news cycle down to
about 15 or 20 minutes.