Unfortunately for his argument, Greenspun seems to be unfamiliar with the history of the magazine. He writes:

"Suppose that an idea merited 20 pages, no more and no less? A handful of long-copy magazines, such as the old New Yorker would print 20-page essays, but an author who wished his or her work to be distributed would generally be forced to cut it down to a meaningless 5-page magazine piece or add 180 pages of filler until it reached the minimum size to fit into the book distribution system."

This is simply untrue-- there have been, over the past 500 years, many magazines and journals publishing 20-page pieces. The shortening of the average magazine piece is an artifact of the past 75 years. To view the history of publishing as one monolithic period from Gutenberg to the Web is absurd.