The thing is, Kara almost certainly has clearly articulated, rational, objective arguments for the design decision in question. If she didn't, she wouldn't be making the decision in the first place. (If she's prone to making decisions willy-nilly with no idea why they're being made, that's a different issue.)

So from Kara's point of view, you're getting just as emotional and defensive about, and ignoring clearly articulated, rational, objective arguments for, the decision as you claim she is. Which is the point of the article - if someone goes into a discussion assuming they are the only one who is "objectively correct", they've already failed.

I've used the method outlined in the article very often in my career and it almost always works. Often it turns out I was right and we shouldn't have done X - but sometimes it turns out that Kara knew something I didn't, and X worked out way better than I expected.