They are rules for a more civilized age. I'm sure they weren't allowed to play music on the radio or be interrupted by a phone while working, either (phones did not exist, I know). The managers probably didn't doomscroll on their phones. You couldn't backstab someone in secret. Everyone knew who the other guys in the office talked to. You had jobs that, if you stayed long enough, paid you a pension. You left your family alone, trusted the neighbourhood much more and it's likely many of your colleagues lived near you. Your corporation probably had to deliver results, couldn't bs its way out.

With a new axis for communication (phones with constant internet access) all these rules have been discarded forever.

I think you're looking through rose tinted glasses about the backstabbing and knowing who people talked to stuff. I suspect office politics in a form somewhat similar to today have existed since offices were invented.