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.
