Most of the time, these people aren't 'yelling at children' but rather complaining about it on blogs like DR and the Saltmines, and here. Many times, these people haven't even posted on site to the person in question, they just want to vent.

To me, I think the issue is that the 'but they might be a *kid*!' sounds a bit too close to 'kids will be kids' that is often used to excuse behavior that SHOULD be stopped.

Also, as an aside, I thought I once found a place that said, but can't find it now, but what do the acronyms NAYRT and the like mean (I am pretty sure they are about replying and identifying people, but acronyms and me? Not friendly at all)