Please label it "the gruseom button".
When someone points one of these issues out, I often feel bad about it. However, I usually don't edit my comment to remove or reword the offending portion because I think it's rude to the person replying and, oddly enough, those who later read it. Because they've made a good point, if I fix up my post it breaks continuity, possibly makes them sound like an idiot, and feels like I'm trying to cover up my lameness.
If I got a similar note that was private I'd feel free to make the changes without as many of those worries. Especially without concern for how they'd take it as presumably they're looking for me to shape up not score points on my misbehavior. I also think that some people that might say something are loathe to reply publicly in fear of just making it worse.
Of course it could seriously backfire if people used it just to be mean back without fear of the community observing. But it seems like it might be worthy of trying.
I think some people here are learning that hugely self-confident, strongly opinionated, obvious writing tends to spark a strong agreement reaction on the readers, who quickly upvote a comment that adds nothing to a discussion. These are a problem, as they encourage snark and posing over effectively arguing things out, but they are very hard to treat as disagreeing with them is likely to cause knee-jerk reactions in many upvoters.
While I agree with the general case, in my specific case I called somebody an "idiot" out of anger and tptacek called me on it. It was quite mortifying and I've tried to watch my words since.
But anything that encourages feedback and discourages defensiveness will be effective.
I never see "nice" tellings-off. A "nice" telling-off might be: "reader123, this comment is mean. please be nicer"