It's Harry talking about Blame, chapter 90. (It's not very spoily, but I don't know how the spoiler syntax works and failed after trying for a few minutes)

"That's not how responsibility works, Professor." Harry's voice was patient, like he was explaining things to a child who was certain not to understand. He wasn't looking at her anymore, just staring off at the wall to her right side. "When you do a fault analysis, there's no point in assigning fault to a part of the system you can't change afterward, it's like stepping off a cliff and blaming gravity. Gravity isn't going to change next time. There's no point in trying to allocate responsibility to people who aren't going to alter their actions. Once you look at it from that perspective, you realize that allocating blame never helps anything unless you blame yourself, because you're the only one whose actions you can change by putting blame there. That's why Dumbledore has his room full of broken wands. He understands that part, at least."

I don't think I understand what you wrote, there AnthonyC; world-scale problems are hard, not immutable.

Having a keen sense for problems that exist, and wanting to demolish them and fix the place from which they spring is not an instinct to quash.

That it causes you emotional distress IS a problem, insofar as you have the ability to perceive and want to fix the problems in absence of the distress. You can test that by finding something you viscerally do not care for and seeing how well your problem-finder works on it; if it's working fine, the emotional reaction is not helpful, and fixing it will make you feel better, and it won't come at the cost of smashing your instincts to fix the world.

"A part of the system that you cannot change" is a vague term (and it's a vague term in the HPMOR quote as well). We think we know what it means, but then you can ask questions like "if there are ten things wrong with the system and you can change only one, but you get to pick which one, which ones count as a part of the system that you can't change?"

Besides, I would say that the idea is just wrong. It is useful to assign fault to a part of the system that you cannot change, because you need to assign the proper amount of fault as well as just assigning fault, and assigning fault to the part that you can't change affects the amounts that you assign to the parts that you can change.