Coming back to the parent claim. You could never trash the Amiga OS because as long as you had workbenchs disks you could reboot the OS just fine and the ROMs were always safe.
Almost all 1980s computers booted the OS from floppy. If they had a hard disk at all, then if you trashed the OS on the hard disk, you could reinstall from floppy.
This was true of Amigas, Unix machines, Commodore 900 series, and all IBM PC-compatibles whatever they were running: PC DOS, MS-DOS, DR-DOS, Windows, OS/2.
You can't boot an Amiga into a full usable OS without at least 1 floppy disk, which means a floppy drive to read that disk.
Same for any PC compatible. Same for any Unix machine.
The point being that you could boot an Acorn RISC OS computer into the full unrestricted multitasking GUI, with networking, without any disks. Without even
having a floppy drive, or a hard disk, or _any disk drives of any kind_. You could physically remove the drives and configure the machine to know it had none fitted, and it would boot and run apps from its built-in ROM drive.
You can do that on an Atari ST as well, with a lot of errors you need to cancel, but there was no multitasking and no network access so the result could not do much. No way to load apps, no way to attach to a machine to load any.
On an Acorn Archimedes with no drives, you could boot, run the text editor, write a letter, open the paint or line-art apps, draw pictures, open the music editor, write a tune, save all those files onto a fileserver, print them out, and then cleanly shut down.
No hard disk. No floppies. No floppy drive. Entire OS and GUI and core apps, in ROM.
