Is this something people even want in content driven sites though? Imagine reddit in real time, it would be a mess and impossible to keep track of what you last read.
Why should users have to click refresh for pages to load more comments or to see when someone replies to you? The fact that reddit does not do this is not evidence that it would be confusing.
Because sites that distract me from what I'm reading to tell me that there are new comments are extremely annoying.
Sure, you could add, say, auto-loading for new comments when you reach the bottom of the page, or setting the message icon to orange when you get a reply, but that hardly requires a full-blown web app, it's a simple addon to a static site.
I have, and it works ok when there is a ton of concurrent users. But on the other hand, I don't think the UX of telescope is any better than reddit's and in some ways worse (example: clicking on a post with a large amount of comments cause the page to pause without any visual feedback. This could be fixed, but is any better than just a regular link?)