The catch with immutable linux is that it can be hard or undesirable to install some core parts like window managers or docker.

So much better approach is to get most of what you prefer by picking right distro. On the other hand ublue makes it very upproachable to make such distros (even yourself). Thats why there are so many of them.

Maybe. The appeal of distros like these is lost on those who know linux well. If you are new to linux, the difference between Aurora/Bazzite/Bluefin and base fedora (silverblue, kinoite) can be like day and night.