I've always wondered this: why release on a schedule at all? If people demand a certain new feature ("[this will] bring you new features more quickly"), it can just be brought out as it's ready, instead of having to wait an average of 3 (now 2) weeks before it can be released? And why does this have to increment the major version, since when is every single update backwards incompatible?
For server-side software, it's easy enough to do multiple releases per day, because you have full control over the environment, and all the work is internal. But for desktop/mobile software like this, having multiple releases per day won't be efficient in terms of bandwidth, load, or user experience.
And each browser version has other external costs, like documentation and support. Right now it can be hard to solve a problem like, "How do I do X with Firefox" because the answer varies by version. The more versions you have, the harder that is.
Or can you imagine trying to triage and verify bug reports if there are, say, 3 new Firefox releases per day, and people could be on any one of dozens of versions because they don't quit and restart the browser very often? We can imagine solutions to these problems, of course. But I think getting a release cadence below weekly for desktop apps will be a very long road.