Earlier quoted context omitted.
Have you ever written a paper for publication? HTML doesn't support the necessary features. Citations in various formats, footnotes, references to automatically numbered figures and tables, I could go on and on. HTML could certainly be extended to support those, but it hasn't been. That's why we're talking about this.
Come on are you serious? HTML/CSS is more powerful than TEX or PDF. https://csszengarden.com/
It doesn't really matter if HTML/CSS is more powerful at a hundred other layout things, if it doesn't provide the absolute necessary features for papers.