> It might sound absurd, but on paper this should be the best way to approach the problem.

On paper yes, but for electronic documents? ;)

More seriously: PDF supports all the necessary features, like structure tags. You can create a PDF with the basically the same structural information as an HTML document. The problem is that most PDF-generating workflows don’t bother with it, because it requires care and is more work.

And yes, PDF was originally created as an input format for printing. The “portable” in “PDF” refers to the fact that, unlike PostScript files of the time (1980s), they are not tied to a specific printer make or model.