As someone who runs 7 servers in different datacenters (including cloud, local, and 2 in my home rack), being able to test and update on one system, then push that update to all the others, is a dream. Immutability is a step in that process, since it prevents weirdness from creeping in between updates. My only gripe right now with the options is they all still feel bloated. I miss original Rancher. All I need is Docker/Podman, and maybe wireguard to string the servers together. Likewise, my data hoarder computers need only zfs and enough on top to link them safely (so, wireguard). If I could focus on 2 stacks that I can push out elsewhere easily, I would be soooo much happier. Sain immutability tools are honestly magical.