The system files aren’t writable, instead you download a new system image when you want to update. No dependency hell or weird issues because these system images are all tested. Your system also keeps one or two old ones around and if by some chance something does go wrong you just select the old one at boot.

Downside is you’re more limited on installing software. You can force install things the traditional way but that kinda defeats the point. Instead you have to use things like FlatPak or AppImages which covers most GUI apps you could want. For command line apps you will have to use something like DistroBox.

It’s a trade off but for casual desktop users it is super stable and pretty simple. Updates come out daily (depending on distro) and they just get all their software from the software center app with a nice GUI.