Part of DeBoer's complaint is what feeds this problem in my opinion:
The second axis of neoliberalism, constitutional neoliberalism, is the reflexive antileftism within the ideology. This is the tendency of the neoliberal to assume the superior seriousness of the man to his right and the utter moral and intellectual bankruptcy of the man to his left. This is the sneering, superior neoliberalism, [. . .] The neoliberal economic platform is enforced by the attitude that anyone embracing a left-wing critique of that platform is a Stalinist or a misbehaving adolescent. This is the critique of the Very Serious Person: there is a very narrow slice of opinion that is worthy of being considered reasonable or mature, and that anyone who argues outside of it should not be given a seat at the table of serious discussion. Genuinely left-wing opinion is not to be debated but to be dismissed out of hand.
Not only is this not an honest intellectual approach, it is also counterproductive to those who favor "Centrist" policies, as I do. Consider the debate about The Deal. The DC Establishment, pundits and bloggers, predictably rejected out of hand the idea of merely letting the Bush tax cuts expire (and indeed, Ezra Klein led the charge of trumpeting The Deal as a great stimulative policy victory.)
This approach is manna for those who favor The Norquist Strategy of starving the government of revenue in order to demolish the social safety net.
Now, if you are a Third Way/DLC type, then marginalizing arguments to the Left of you makes sense. But Yglesias, Drum, and even Klein and Chait, are not Third Wayers. But their approach is beneficial to the Third Way agenda in my view.
How much of this is due to a reflexive defend Obama and the Beltway Dems mentality? I think more than these folks would care to admit. In any event, if DeBoer's article leads to some self reflection on these points, some good could come from this exchange.
Speaking for me only