There also seems to be an impermanence to commenting on a video, especially one that's popular, because responses (unless sufficiently up-voted) don't stick around, and there's no way to easily search through them.
So a YT comment stream takes on a party line vibe and (IMO) there's not much point taking the time to write something thoughtful.
Mainly when I have commented is on videos on niche subjects when I'm reasonably sure the video poster/artist/producer will see it.
There was a period when I was able to Have A Conversation in YouTube comments but I was never able to do it more than a few times. On the other hand, I see people having legitimate conversations on random occasions quite frequently.
So a YT comment stream takes on a party line vibe and (IMO) there's not much point taking the time to write something thoughtful.
Mainly when I have commented is on videos on niche subjects when I'm reasonably sure the video poster/artist/producer will see it.