Could the browser tackle this? If I understand it correctly, in broad strokes, nothing comes down unless the browser asks the server for it.

I'm dating myself, but when I first learned about HTML, the idea was that text would be organized so the browser could make it more readable for you, based on your needs. For instance, a deaf person could use a text-to-speech browser, and perhaps the heading tags would help them navigate the document.

Today's web page simply treat the screen as a graphical canvas.

In those old days, I also learned that having a crummy obsolete browser for my crummy obsolete computer actually sped up browsing because my browser was simply incapable of downloading the stuff that ate bandwidth.

That is correct. justread will save you data compared to loading the original page. No javascript, ads, extra images unrelated to the article etc. It does, however, keep the images, since often they are an interesting part of an article.