It wouldn't work with modern Ubuntu releases. They're all container based and Canonical has no control over Firefox and many other packages on those platforms.

It wouldn't work with modern Ubuntu releases. They're all container based and Canonical has no control over Firefox and many other packages on those platforms. They've given up and that's upstream's job. So there would be extreme friction on modern Ubuntu container based releases over 15 years. But not for 14.04. 14.04 was released before all this container nonsense and it is a coherent userspace canonical packages. I can tell you from person experience the last decade (using the free version) that it's worked flawlessly.