which explained the 2012 presidential election loss with the following (no doubt among other reasons):

"We have become expert in how to provide ideological reinforcement to like-minded people, (...) but we have lost the ability to be persuasive with, or welcoming to, those who do not agree with us on every issue."

That pretty much sums it up. I think the Democratic Party (as a whole, of which the liberals you describe are only a part) suffers from that to a much lesser extent, because they would be more directly hurt by a similar stance - outside New England (or even there, really), the real "RINOs" and genuinely liberal Republicans are quite scarce in national politics, while the Democrats still have tons of "Blue Dogs" and other (relative) conservatives. Plus two crucial groups of voters (African Americans and Hispanics) who are overwhelmingly Democratic, but not overwhelmingly liberal.

Anyway, that's not exactly what your article was about, it just reminded me of it. The author has several good points, including the one about how conformist supposedly rebellious students often are. I'm not sure I'm convinced that liberal adults consider themselves so rebellious, though - that's a bit hard to reconcile with the tendency of many of them to figure that any sane and intelligent person would agree with them, which the author mentions elsewhere. If anything, I'd say it's conservatives who I most see patting themselves on the back for not buying into the dominant narrative of the liberal mainstream media (which is rather more convincing when it comes from those who manage to avoid falling hook, line and sinker for the propaganda from the conservative media channels instead, but that seems to be a minority).

But of course I agree with the conclusion - conservatives and liberals don't need to agree on things more, they just need to agree to disagree more, and have some more understanding for the other side's ways of thinking and motivations - in short, accept that someone can arrive at the opposite conclusion in most any serious political debate without being stupid, insane or of bad will. And that even when there are only two sides on a given issue, there are still infinitely many political positions at the end of the day because people who agree on some things will still disagree on others, and vice versa.