The largest problem with the JSON-type WYSIWYG implementation of editors is that they all have their own custom implementations and conventions of how they represent the DOM via JSON. Quill was one of the first (that I was aware of) to have a complete and somewhat sane implementation therein. That said, since that seems to be the way editors are moving in general, I think it makes sense to go in that direction as well, but choosing should be made with care, determining as many pros and cons of features and technical decisions for the choice as possible.
The topic that covers editor.js is: https://processwire.com/talk/topic/24876-pw-30170-– core-updates/
There was another one (I believe the next update by Ryan in News & Announcements) that partially continued the discussion, but most of it, if I'm remembering correctly, was here.
Statamic's Bard uses TipTap, and prior to that used ProseMirror (TipTap uses ProseMirror under-the-hood which is likely why they were able to easily switch to TipTap; the same underlying JSON representation).
EDIT:
I think @jploch's module, PAGEGRID, originated out of that discussion. 🙂