Supposing I just want to create an internal tool that allows me to collaborate in realtime with my colleagues on a document (multiple cursors, everyone editing at once) and I have to do it in an existing browser because I don't write C++ and only have a few weeks to deliver - how would I do this without JS? Also, it needs to work on Android, iOS, Windows, and macOS in FF, Chrome, and Safari.
First, you're moving the goal posts...
> so you don't have to write JS
... and attacking a strawman. (No, I'm not worried that I might "have" to write JS. I've written a lot of JS. And I put a lot of effort making sure there was high quality documentation about the language in the early days of developer.mozilla.org—so that other people could have a nice time when they write JS.)
Secondly, you are aware—I'm certain of it—that the company behind Google Docs actually does have a browser.
So your users will need a specific browser to use your Web app?
This goes against a primary advantage of Web apps... They work on many different browsers/devices*
No. For the use case mentioned (editing and sharing docs in Google Docs), no one would be using a Web app, because there isn't one anymore. With the browser itself able to do directly what Google Docs is being used for, there's nothing left.
* If someone really wanted to be a stickler, they could point out that that you've set up Google Docs to fail your own rubric, since it involves indirect editing. The browser itself has no direct role in the editing process. It only manages to do so by fetching and executing the minified bundle on the Docs site.