So I don’t think there’s much merit arguing about what doesn’t exist any longer.
This kind of fairly idealistic thinking is so far from the ordinary web development norm that you have to go past "supporting that version of IE with 0.7% market share" to get to it.
I politely disagree, the problem is we have made websites a javascript hellscape with all that original intent broken by design.
And I politely disagree right back. My particular problem with this has to do with purchasing. When I make a purchase at work, I need something I can attach to a purchase request as a quote. Note that this is often not a formal quote, but rather evidence of what whatever I want to buy will cost.
A simple way to do this is to print a shopping cart to PDF and attach that to the PR. Some web sites do this just fine and others do it horribly. They should do better.
But to expect every author also upload a PDF? I mean, TeX is great for what it is, but there's a reason _the web_ adapted print stylesheets.
Even if (La)TeX (or Typst, or Postscript or anything else) were easy to learn, you're left with maintaining 2 copies or a compilation system which is also a challenge.