[mmh0000]

I can give you a bunch of things that can't be simulated in a container:

* Boot problems, such as: GRUB config/install errors, kernel parameters, init startup errors, blocking processes

* Many network scenarios, such as: PXE issues, multipath, load-balacing, anything requiring configuring network interface settings, firewall configuration.

* Resetting an unknown root password

* Booting directly to bash

* Filesystem mounts through fstab or systemd mounts

There's probably more I could think of, but I think that's a good list.