This isn't a defense of Jonah Lehrer in the sense of arguing that he's blameless for his fairly egregious pattern of "self-plagiarism" (or, as he might prefer to put it, his pattern of "high-fidelity recycling"). And I'm not addressing at all Lehrer's alleged instance of actual plagiarism, which is a much more serious matter. My only point is that the current journalistic environment encourages recycling, and renders his misdeeds less surprising than they'd have been in, say, 1987, when I was his age and had never heard the word "internet".
There are basically three new factors at play:
1) More than before, success in journalism is about sheer quantity of output. In 1987 if you named the top young (say, under age 35) pundits and essayists, a number of them were people averaging maybe 1,000 or 1,500 words a week of output, perhaps in the form of a single weekly column. Now the young superstars average more like 5,000, even 10,000 words a week, broken up into 10, 20, 25 pieces. If you're young and you want to keep getting noticed, you've pretty much got to produce at this volume, unless you're sitting at one of the handful of remaining elite perches (The New Yorker, The New York Times)--and even at these places, quantitative expectations are rising as writers like Ross Douthat, Paul Krugman, and Hendrik Hertzberg blog in addition to doing their traditional writing. (And if you are going to try to get by on merely a couple of thousand words a week, you'd better get at least another 1,500 words onto Twitter to make up for it.)