Because all changes are transactional so you can easily revert to a previous system state if you break anything

With fedora atomic, lets say i wanted to try out kde desktop for a while. i would first pin my current build so i can roll back to it if i dont end liking kde with

$ sudo ostree admin pin 0

Then i would rebase to the kde branch with

$ rpm-ostree rebase fedora:fedora/39/x86_64/kinoite

Then just reboot. That’s literally it and i would have a kde system with all my layered packages and i could roll back to my old system at anytime.