...because, it makes you sound smart and thrills the multitudes of thought-hating, reason-eschewing (eschew: to shun) individuals that comprise your audience.
Joe Nacera, in his article here, accuses Obama and Conservatives of having offered no real solutions to high unemployment. He argues that Conservatives continue to offer non-solutions based off of tax-cuts for the wealthy, despite mounds of evidence to the contrary. For Joe, "mounds" of evidence consist of such brilliant and highly reputed sources like the Huffington Post, and The Atlantic. One journalist with left-leaning political views citing other leftward leaning journalists does not make a strong case any more than would an academic citing only his or her own work in a paper.
Joe should at least acknowledge that there is a certain level of corporate taxation that would push producers of goods and services from the market. Once one admits this level exists (we may not know what it is exactly) then it follows that once beyond this level, a decrease in taxes will serve as an incentive for producers to reenter the market, and thus, lower unemployment.
What Joe should really concern himself with is whether we are beyond this level, or not. That's where the debate is, and where contributions to that debate are useful.