Well, books also continue to fail a lot of people
> Not all of these are even true of physical books - people have been bookmarking them and scribbling in the margins for ages.
All of that is true for physical books, if you're limited to tiny margins and can't easily find your margin scribbles later, then it's a format fail, you just continue to use the same flawed logic "done for ages = good"
> And also, e-books and PDFs exist, for the people that prefer them.
Which mostly repeat the paper medium, so fail to solve most of those issues
> As for the "tailoring to a specific reader" and "tracking understanding", that's a problem for any learning resource, as people are incredibly varied.
Yet it's especially a problem with books
> In general, for a given topic one should check out different books
In general one should not limit oneself to books, even for just a starting point
> Books being hard to edit and/or collaborate on could maybe (if it's even true) be a problem for authors, but why does it matter for readers?
For example, to remove "sections that are obvious", add "exercises", find reference to "other sources", see explanations from other readers etc.
> there's no problem with supplementing a book with e.g. a website where you can find interactive visualisations, etc.
The problem is it's a big limitation of the format, and you can't integrate it well if you have to switch back and forth
> also: simply not every topic needs complex interactive visualisations
Which topic do you think can't benefit from one?