Comment by acdha

That'd certainly make sense — a lot of what we see now are fossils like that, frozen in the amber of legacy systems.

That would be a reasonable precaution in the era before recording devices became cheap, tiny and ubiquitous (or capable of doing signal processing in real-time) – just as changing passwords monthly made more sense in the 1970s when shoulder-surfing was the major threat and lack of remote access throttled guessing rates even more than slow CPUs. (Repeat for plastic ID cards before you could buy a printer at Costco, etc.)