[ascagnel_]

This wouldn't surprise me -- some stuff, even if it's older, is still in use because it works well. Numbers stations[0] are still a thing because they're (relatively) cheap to set up, reliable, and virtually impossible to trace the source.

[elvecinodeabajo]

The great old engineering mantra: 'If it works, don't change it'.

[ambicapter]

You forgot to link your citation.

[Crespyl]

I'm not ascagnel_, but the Wikipedia page covers the topic pretty well: https://en.wikipedia.org/wiki/Numbers_station