Marginalization of journalists, academics and other professionals is one of a number of techniques used to delegitimize inconvenient facts.
One of the better commentaries on the subject is Paul Craig Roberts' sign-off column found at http://infowars.com/good-bye-truth-has-fallen-and-taken-liberty-with-it-2/
Roberts, a Reagan assistant Treasury secretary is credited with drafting the Kemp-Roth bill and is a former Wall Street Journal columnist. But he's been marginalized for such things as wondering why there is a need to make a taboo of criticism of government 9/11 reports. His bio is found at http://en.wikipedia.org/wiki/Paul_Craig_Roberts