It's extremely easy to convert HTML/CSS to a PDF with the print to PDF feature of the browser.

All papers should be in HTML/CSS or Tex then just simply converted to PDF.

Why are we even talking about this?

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.

What are you talking about? No one’s writing their paper in HTML.

The problem is having the submissions be in TeX and converting that to HTML, when the only output has been PDF for so long.

The problem isn’t converting HTML to PDF, it’s making available a giant portion of TeX/pdf only papers in HTML.

If you’re arguing that maybe TeX then shouldn’t be the source format for papers then I agree, but other than Typst (which also isn’t perfect about HTML output yet) there aren’t that many widely accepted/used authoring formats for physics/math papers, which is what ArXiV primarily hosts.

LOL what. You're either trolling, or you've never written a paper in your life.

So, uh, where do the HTML versions of the papers come from?

It's easy to convert PDF to HTML/CSS, with similar results.

Either way it gets shoehorned.

Except you can't have page breaks, three links in a row, anchor links.