To argue with myself for a moment, this is one of the difficulties with analysis. Fairly few political commentators know enough to decide which research papers are methodologically convincing and which aren't. So we often end up touting the papers that sound right, and the papers that sound right are, unsurprisingly, the ones that accord most closely with our view of the world. So Alesina's paper gets a lot of conservative pickup, but if it had found the opposite, it would've been ignored by conservatives, or maybe torn apart by experts sympathetic to the conservative approach to austerity, even as liberals championed its findings.

I like Ezra Klein. I think he's an honest guy who really wants to get to the bottom of things. But Ezra seems to labor under the assumption that the truth matters and that there are good arguments and bad arguments based on whether the evidence supports them. Partisans never ever advance arguments because they are true; they advance them only to justify their pre-existing agenda. They are good arguments to the extent that they effectively do it; and bad arguments to the extent they don't.  Some make these arguments naively; some make them cynically. Same result.

It's not about who's right; it's about who has the power to shape the public agenda and the conventional groupthink justification for it.  People who care about uncovering the truth are people nobody listens to. So why would anybody with any ambition speak the truth? If you have any hope of being a player, you have to prove that you're "serious", and that means making it clear to everyone that you've drunk the Kool-Aid.