I’d also be very interested in a browser-based editing feature. It is very important for me to have the full control of the files, and the desktop and mobile versions are very valuable to me, and I use them most often. However I occasionally find myself working on my personal data on computers of other people. This could be at work (at different office locations), on a travel (in hotels, libraries), during a visit of a family or friends. Synchronizing the files locally is infeasible in those circumstances.
Usually I open an incognito window of the browser and have access to all my Gmail & Evernote data, and it would be very important to me to have the editing access to my Obsidian data as well. When I work in Evernote, I usually edit several notes on two of my screens, while keeping a bunch of other notes open on the other two of the screens. The web-based editor would make it possible with Obsidian as well.
We already have our data at Obsidian cloud servers with Sync and Publish, so the web display and navigation are already implemented. The only thing left to add is an editor, I don’t think it would be a large overhead to implement.