The professional press will not perish, even though only the sedentary rich will care to subscribe to paper editions. Had Deep Throat blogged, his conspiracy theory would have been lost among many. Wikileaked he could have. But much of what is worth uncovering is not packaged for leaking. Investigative journalism requires as much dedicated research as police investigations, scientific studies, and film productions do.
In addressing strangers, the credential "I am a reporter for the Washington Post" reassures more than "I am a blogger" does---which rather resembles a confession, akin to "I talk to myself" or "I have imaginary friends." Reporting requires exuberance that a collegial environment incites, and the critical judgement that a detached editor exercises. Passion, censorship, and a long-term outlook rarely combine in a lonely investigator.