When I wrote the original post (2014), we had spent a lot of time experimenting with mobile browser APIs for editing text. We talked to browser engineers directly. We concluded that rich text editing would be an unacceptably bad experience on mobile web without browser bug fixes.

Since then, more data model based editors have appeared, like ProseMirror and Trix. I’ve heard that they’ve had a lot of success using MutationObservers to track input on mobile. And mobile browser APIs have gotten a lot better (thank you short phone lifespans, I guess?). But I haven’t experimented with this myself.