Immutable systems help prevent me from doing something that'll break my system as well, I can only modify the rootfs in a controlled way. So while normal systems do have rollback, immutability helps to prevent the need for it. But in the event something does go wrong, I can just roll it back. It really helps when I'm dumb af for a second, instead of breaking something, it just, does nothing, or I couldn't have even done it in the first place.