There are fantastic, beautiful interactive experiences (for lack of a better word) that are obviously not documents (they can't be represented on paper, there is code running) but they're not really applications, either (they are fully offline, self-contained, state that's only evident on the page).
But they are, universally: dynamic.
Examples: - https://ciechanow.ski/mechanical-watch/ - http://worrydream.com/TenBrighterIdeas/ - even : https://neal.fun/space-elevator/
This is what I think the future of textbooks and presentations should be. But I think part of the problem is that not only do we not have tools geared toward creating them, we don't even have a name for these things. If we say "document", they flunk the pdf test. If we say "web application", they are lumped into the same lumbering category as office docs and enterprise software.
Maybe Nota is a step in the right direction. But it'd be an even better step if it didn't call itself "21st century documents", if for no other reason than to defend against the valid criticism you levied against it.