We also noted that the supplied key locks the power button, as it did on some ancient systems.

The ancient systems I knew didn’t have a power button, and instead power was controlled by a physical switch on the high voltage side of the power supply.

The key actually locked out the keyboard, which was possible since the keyboard had a dedicated connector. So you could still turn the computer on, but you really couldn’t use it.

I suppose locking out the power button is a suitable replacement for a modern case.