That's not the point. 90%+ of the webpages I visit are essentially static documents. They can easily be treated as
data, not code; even the UI description could be omitted and reasonably reconstructed from the actual page content.
This webpage? It consists of a title and a link to an article, followed by a series of comment objects. Each comment contains some text, an associated author, a timestamp, and possibly a set of child comments.
This exact arrangement of data can be found all across the web. If you take any blog article, it consists of this same layout, only instead of a link to the article, you have a bunch of text and/or pictures.
It arguably took more work to design a product (the web browser) that can parse html, apply CSS styling, parse and execute Javascript, and tie all those pieces together with the DOM than it would have been to just have webservers pass a loosely annotated version of the page contents to the browser and let the browser decide how to render and interact with the content on its own accord.
The point is, running an "app" on the web is largely BS. If you think your blog, news site, or forum is sufficiently different from the thousands of others out there that it warrants an entirely new application (as opposed to just different styling), then you're full of yourself.
And if we had taken that simpler route, I wouldn't have to spend days designing a trivial blog site. Websites wouldn't all be so jarringly different (which they largely are, and unnecessarily so). I could get straight to writing my content, because browser defaults would actually be sane enough to do the dirty work for me. And the resulting UI would be more accomodating to the user than anything I could whip up with "modern" web technologies because the browser has access to the user's [language, color, contrast, font-size] preferences. Not to mention how much more accessible it would be to the visually (or otherwise) impaired.