Being able to roll back updates/upgrades that go wrong, is not just fixing a minor inconvenience. There's also something about the critical part of the system being less mutable. Desktop Linux has been way too easy to break in the past.
Tumbleweed is a conventional distro. You're root, you can do whatever you want, you have full R/W access to the entire FS, and updating is by installing lots and lots of packages into the live OS while it is running.
Aeon and Kalpa are immutable: the root fs is largely R/O even to root, and you cannot install or update packages on the running system. To install packages into the OS itself you must reboot, and installation is transactional -- it can automatically undo changes that prevented a successful boot.
