I don't understand. Why not build most of the functionality in HTML + CSS and use JavaScript only for interactivity and "real time"? Hacker News is a very good

I don't understand. Why not build most of the functionality in HTML + CSS and use JavaScript only for interactivity and "real time"? Hacker News is a very good example of that done right. I have JavaScript disabled and I can use the site just fine. The only thing I can't do is collapse comment threads.