It may have been in the '70's when aluminum wires were installed in many applications. Al has different thermal expansion behavior than copper so terminal boxes and connections would loosen which led to fires. May have been mitigated with Al-friendly box designs but Al wire didn't last long in the new construction world.

I despise the twisted (wire nutted) connection from a safety/reliability standpoint.

At one job the A/C circuit kept blowing a fuse in the panel for the compressors on a very, very hot summer day. I used an IR thermometer to show that one of the 3 fuses in that box was running quite hot. So we called an Electrician who tightened the terminal screw and brought the temperature back to normal. (I wasn't brave enough to work on live 220V circuits.)