If you're using gnome/kde, I see no reason not to run immutable, the advantages of not being immutable are that you can piece together your system, if you're running i3/sway/whatever, being able to choose your panel, your launcher, etc actually has value.
The advantages of immutable are that you'll never end up with a broken system, you can easily roll back to a not broken one if something does break, and the system is separate from your apps.
I was able to break fedora silverblue by messing file permissions in the home directory. Toolbx then stopped working, without which the distro is unusable.
You can also make chaneges in /etc and similarly ruin your system.
Just saying they aren't quite as "unbreakable" as advertised.
all changes in etc are snapshotted with each update so you could just roll back to your previous version and it would fix it.
I assume you meant you messed up permissions in your home directory, and yes that is pretty much the only place you can permanently mess something up with silverblue.