Let's say you're a Nazi and all your friends are too. Then you start wondering if Lebensraum is all that important, but your friends all click ಠ_ಠ: demonstrating why mechanisms that enforce conformity do not enforce correctness or virtue.
I don’t think that the author’s suggestion was meant to enforce correctness or virtue, but rather to provide a means for your friends to nudge you out of extreme behaviors.
Now, if one’s friends have opinions that the rest of us find to be terrible, then maybe it’d be better for that person to be able to drift away easier. But I think the thesis here is that most of us aren’t at the extremes / aren’t in bubbles mostly comprised of extremists, and a private-hairy-eyeball would perhaps help many of us from radicalizing our dialogue.