I like the idea of long-form comments. I never really tend to read comment sections on other platforms because I know most of its content is either reactionary or just trolling. Well, it's not true. Sometimes I do open it for fun, to see how many people commented something that's nothing to do with the main purpose of the article.
As you have written on Engagement has it hard, engagement is indeed hard. I've also came to a similar conclusion on Engaging with posts on fediverse. I got very surprised when I moved into write.as to see that other people were actually quoting me on their posts and were adding to the discussion. I don't think I've quite seen this somewhere else. I like this idea of opening read.write.as and looking to see what other writer are talking about, seeing if you have been mentioned, seeing if a conversation is progressing. Yet it's so easy to miss something. If you don't read everything, you might miss out on someone quoting you. Is it a bad thing? I would have said so a while ago. I'm not sure anymore. It creates excitement.
My hope is that such a system will beget real engagement here. It does not have to scale. It just has to matter.
I couldn't agree more what that statement.