That depend on your needs.. linux can do live update if you need that, usefull on servers..

But atomic versions as more target to desktops or containers where you need to have know working setup and when you upgrade you replace it by newer one..

So you dont update per se... You install the new version in a separated partition and boot into it the next time you restart.. Same with containers, you just destroy it and recreate with the new version..

If the new version fail you boot back to the old original version that is know to be working and have not being replaced..

The ideia is to ensure a known to be working system is always available..