In a sense OP wants E-ink screens and org/vimwiki/markdown. Styling is where the problem it claims to criticize begins; if you want a truly accessible hypertext book, then you don't need styling, the user should be in charge of this, and the default theme would be whatever easily readable font, black on white, headings 36pt bold, paragraphs 14pt regular, every elements as blocks. Epub, in usage, is actually a cool format and I almost prefer this type of "browsing" experience than what websites proposes.
Or maybe OP wants higher level CSS and HTML, and this is a problem because this leads to the invention of a new language with yet another complex ontology that claims to be "simpler than its lower level counterpart" but is not.
Of course you could create some markdown with basic styling options, but I am pretty sure learning basic html and css is not that more complex than learning that specific markdown and how to operate it to finally get a website served on a specific server.
Web and styling became complex exactly when occurred the encounter between what was styling on the web in the 2000s, the emergence of the nowadays variety of devices that are able to browse it and the actual way people interacted with smartphones.
Today our browsers are almost OSes and it's almost like the complexity of what you can share with them is superior than the complexity of you could create on a 1990 pc natively. I mean, you can run godot engine on your browser : you can develop prototypes of projects with your friends just for fun, create your own private platform for communicating with people you like.
I notice a lot of hate toward JS, but honestly when I first stumbled upon it I felt like a dream came true; it gives you the power to create experiences and share them almost effortlessly, and the fact that bigTechs decided to make boring websites on crazy over-engineered frameworks doesn't change anything to this.