(disclosure: I work on Quarto) I 100% agree with you. It's partly why tools from the Quarto lineage (knitr, rmarkdown) work hard to make popular latex features like crossreferences work in HTML and other forward-facing formats. At the same time, if you haven't tried Typst, my opinion is that doing so is an afternoon well spent. It's an impressive system even early in its development stage. I'm hoping it finally displaces LaTeX --- and I'm a former academic having written about a hundred papers in LaTeX!

I have high hopes for Typst, but I'm very disappointed they didn't design for accessibility from the start (and nice HTML would have done the job). It's shocking how inaccessible latex's output is, and yet Typst manages to be even worse!

Quarto's html output on the other hand is generally lovely for accessible output.

As an author, PDFs are indispensable. A good chunk of folks still prefer to read physical books.

When I migrated my own tooling from rst, I was looking at Quarto but ended up rolling my own pandoc/md tooling.

Why not use epub?

Hard to print a good looking physical book from EPUBs. (I generate EPUBs too.)