> I feel much safer telling people to “just try stuff” when I know there isn’t a risk of them breaking everything and being left with an unbootable machine

On which non-mobile OS is this true? It's certainly NOT safe on Mac/Windows/Linux to "just try stuff". I can trivially delete all of your data and/or upload all your .ssh files and Documents by "just try it"

If you are running an immutable system like Bazzite it is significantly harder to get yourself into an unbootable state by accident, since if your system-wide change does actually break the machine, you can just boot into an older one. NixOS is quite a bit different, but likewise it is really hard to make the system unbootable just by making changes, since I can just boot into an old generation. I haven't used rescue media for my own machines in probably 5 or 6 years now.

I’ve found a big performance boost by running:

    sudo rm -rf /

By running libre software exclusively and an encrypted hard disk, just try.