Noting and agreeing that most of our discussion here is about splitting hairs and this is just for fun...
...on the way home I thought of another twist to add to it.
The part about a 180° sound stage…only translates to headphones or when standing directly in-between speakers. When we use monitors...we are actually sitting within a 60° degree range --Left to Right-- of the equilateral triangle mix position.
So while panning 180° IS hard right...it doesn't quite sound 180° through monitors from the mix position.