I like Arxiv and what they are doing, however, do the auto-generated HTML files contain nothing more than a sea of divs dressed with a billion classes?

I would be delighted if they could do better than that, with figcaptions as well as figures, and sections 'scoped' with just one <h2-6> heading per section. They could specify how it really should be done, the HTML way, with a well defined way of doing the abstract and getting the cited sources to be in semantic markup yet not in some massive footer at the back.

There should also be a print stylesheet so that the paper prints out elegantly on A4 paper. Yes, I know you can 'print to PDF' but you can get all the typesetting needed in modern CSS stylesheets.

Furthermore, they need to write a whole new HTML editor that discards WYSIWYG in favour of semantic markup. WYSIWYG has held us back by decades as it is useless for creating a semantic document. We haven't moved on from typewriters and the conventions needed to get those antiques to work, with word processors just emulating what people were used to at the time. What we really need is a means to evolve the written word, so that our thinking is 'semantic' when we come to put together documents, with a 'document structure first' approach.

LaTeX is great, however, last time I used it was many decades ago, when the tools were 'vi' (so not even vim) and GhostScript, running on a Sun workstation with mono screen. Since then I have done a few different jobs and never have I had the need to do anything in LaTex or even open a LaTeX file. In the wild, LaTeX is rarer than hen's teeth. Yet we all read scientific papers from time to time, and Arxiv was founded on the availability of Tex files.

The lack of widespread adoption of semantic markup has been a huge bonus to Google and other gatekeepers that have the money to develop their own heuristics to make sense of 'seas of divs'. As it happens, Google have also been somewhat helpful with Chrome and advancing the web, even if it is for their gatekeeping purposes.

The whole world of gatekeeping is also atrocious in academia. Knowledge wants to be free, but it is also big business to the likes of Springer, who are already losing badly to open publishing.

As you say, in this instance, accessibility means screen readers, however, I hope that we can do better than that, to get back to the OG Tim Berners Lee vision of what the web should be like, as far as structuring information is concerned.