Immutable distros solve a lot of problems and are IMHO a great idea. I love my SteamDeck with SteamOS, I really like Silverblue and OpenSUSEs MicroOS (Avalon or however it is called right now). For my desktops/servers Debian is the best choice right now, but my Thinkpad from 2012 which runs now happily as an entertainment machine is a perfect example where an immutable distro would be much better and practical.
Immutable distros are a solution to a real problem, and this problem is not solved by Ansible/BTRFS etc. Hell, I’ll happily jump ship sooner than later. Of course, YMMV and I don’t say immutable distros solve all problems for everyone, but having this option is great IMHO.