I'm so surprised that all attempts at solutions for "readability" so far seems to have addressed the actual article or post content only. I don't just want to read a sane looking web, I want to browse a accessible and sane looking web.

I'd like to be able to activate a browser mode that cleans up not only the content of the site, but also the structure by creating simple and accessible navigation (perhaps according to html and css rules that I can write myself).

Many sites have a similar type of structure (/about/, /contact/ etc). HTML5 sites with <nav> will hopefully have made this endeavor much easier.

Sites with more complicated structure could perhaps be analyzed by AI and OK'd and corrected by a collective of users (via a browser extension). When the sites has been "solved" by AI and/or it's users, it can be added to a shared database (think something like https://userstyles.org/) that will be automatically queried when you use the site.