On the other hand, military avionics has used waxed nylon cord
(usually dyed black) and made under a MIL SPEC since the 1950s,
prinicipally because it was a neat, cheap way to bundle up wires
that were not otherwise clamped together.

Here's my take on this (I laced a lot of wires
in the 1950s).

Wiring *harnesses* were made to facilitate
interconnection in equipment. Boards of
plywood with a drawing of the harness glued
on were the pattern, and finishing nails used
as guides for the wires. Wires were laid into
this guide according to a printed list. These
wires were usually pre-stripped and tinned.
Then the wires were soldered to connectors
when appropriate, and finally it was laced up.
This served both to constrain the wires, and
to make the harness easier to handle while
it was installed in the equipment. The stitches
or knots had to be done precisely according
to a MIL-Spec. It wasn't a lot of fun, and I
can remember rush jobs where everybody
from the lowest technician (me) to the engineering
manager worked long hours to make those
harnesses! Sure looked nice when it was done!

BTW, we only used white waxed nylon.

73, John - K6QQ