I think on average the tree well explanation is a bit simpler:
I'm skeptical that a pole plant would be the big issue that would drop someone into a well.
Agree about the sound thing though. Even if you are standing up in a well with your face out of the snow -if you are down in a well, people even 10 or 20 feet away may not hear you yelling...
FWIW, I have a +/- 30 foot chunk of accessory cord (6 or 7mm I think) in my pack. Weighs almost nothing and takes up little space. The potential value of this just sort of popped into my head one day ;). Of course it'd be useless if one did not know where one's partner(s) was.