The most straightforward strategy for scaling the mnemonic medium—Turning any web page into the mnemonic medium—can’t be applied to most texts (even new ones) because they’re not published as web pages.
Modern publishers are used to preparing titles for multiple destinations (print layouts, EPUBs, Kindle formatted copies), but few publish them as web pages. Those who do offer online reading usually do so via a (terrible) web-based EPUB reader. O’Reilly is an interesting exception—they present books online as straight web pages.
EPUBs are constrained web pages, though, so anyone who is preparing EPUBs isn’t that far from web publishing.
If you make an EPUB, Amazon deals with distribution. If you publish a web book, you deal with distribution. I imagine that’s a barrier for many.
It would be nice if future books could be made available on the open web, instantly linkable without any kind of barriers. That approach would require some way for authors to make money. I’m not sure what that is. Micropayments for content have a fraught history, but perhaps crypto will change the story. Ads are unhappy solution, and I’m skeptical that they could generate enough revenue. Tipping models work for some authors who publish online, but it doesn’t seem predictable and scalable enough for mass adoption.
So long as traditional publishers are in the mix, I expect most will simply want one-time payments. I don’t know of a general service which would allow you to put a web book behind a one-time paywall. Gumroad does this for downloadable content. It looks like there are Wordpress plugins to do this, but they don’t look highly polished.
If you’re publishing a print book, you use InDesign. If you’re publishing an ebook, Amazon’s made free mass-market tools which can e.g. easily convert from a Word doc. If you’re publishing a web book… what do you do, exactly? Maybe Wordpress can handle the servers, but how are you getting the book into Wordpress? Surely you didn’t write it in Wordpress’s editor.