But there are plenty of videos where that's not the case. There are many excellent scientific and educational videos on youtube, and the comments sections for many of them are excellent. Or were anyway. Periodic videos. Minute physics. Veritasium. EEVblog. Vihart. And so many others. In such places the comments can be civil, interesting, enlightening, sometimes just as good as an average comment on HN. But now those comments are a bit less valuable in general because so many of them are of the form "X just shared this on google+".
Instead of being a response to the creator, some comments are now a shout out into the crowd. And all of this is just jumbled together. It's an incredibly stupid and broken way to handle commenting that is only just slightly stupider than the old incredibly stupid and broken way they were doing commenting.
The idea of freighting around my one and only social circle as some sort of background peanut gallery everywhere I go is, frankly, not interesting to me. The reason I go seek out different channels and different sites is to have different experiences, often with different people. HN isn't my friend-group, and I wouldn't want HN to be replaced by my friend group either, and I value my friends greatly.