PDF is used for pre-formatted content with reproducible layout. HTML is used for dynamically formatted, dynamically laid out and often reflowable content. It's

PDF is used for pre-formatted content with reproducible layout. HTML is used for dynamically formatted, dynamically laid out and often reflowable content. It's debatable whether PDF needs a more modern alternative, but HTML is certainly not a replacement for it. There are several use cases where HTML is not the appropriate choice - especially for carefully laid out documents or books. You can simulate pre-formatted layout in HTML, but it always feels like shoehorning an unintended functionality. LaTeX and Typst are markup primarily for PDF type contents. Something like Asciidoc or even Markdown is more appropriate for HTML type content. You can always switch the purposes, but I never got a satisfying output by doing that.