I’d love if there were different “layers” of meta discussion on top of everything on the web. Every blog and website would have an untold number of communities having discussions that are completely optional for you to view.

Instead of browsing across sites, you’d be browsing across communities seeing the same site.

I started working towards this goal in the latest release: you can now add Reddit as a source, so now when you visit a URL it will check across all subreddits where it's been posted and give you a blended discussion made up from everyone's comments.

I've been working towards building out functionality close to what you're describing. As a first feature, I added annotations where the script looks for HN comments quoting parts of the article and adds a highlighter effect. It lets you instantly see what parts of the text people are actually interested in. It's still a rough beta, but I'm actively working toward that exact vision.

Fun story. Way back in 2008, I tried to make it exactly that. I worked on figuring a way to inject the reddit comments onto any page. Sadly at the time the JS ecosystem just wasn't mature enough to allow users to log into reddit and safely inject it onto the page.

Disqus existed, but it worked because every page was completely independent. The discussion only existed embedded on the page.