It seems to me like it's a bad thing that an accidental rm in an efivarfs filesystem can brick the system, regardless of whether the filesystem was automounted or not.

Windows does not have this issue either.

But on sysvinit if you mount efivars rw for any reason and your hands slip a bit a stray `rm` could still brick your motherboard, so it's not really fair to say that without automounting the issue goes away.