Yes that's also key for network admins - ironically I found when doing my CCNA that my experience years ago on PDP's cli came in handy on ios (the Cisco os).
Eh, that doesn't scale beyond a few devices. There's out-of-band management, yes, but often it's in the form of an isolated management network, which allows automation quite conveniently. Even the serial console is often accessible over a network using terminal servers. You usually also want to be able to download and archive your device configuration automatically using eg. oxidized.
That said, being able to work with standard tools is extremely relevant for debugging problems, still.