It's gratis, but not libre. Some people value this attribute of a software, choosing their toolkit exclusively or primarily so. And for these people, a nonfree

It's gratis, but not libre. Some people value this attribute of a software, choosing their toolkit exclusively or primarily so. And for these people, a nonfree software is a not a replacement for a free software. Also yes, because it's only distributed as a web app, one day it might vanish and that's it. If it were AGPL licenced, for example, anyone could fire up another instance or embed it via Electron, and the software would live on.