I wouldnt even mind so much if people knew to even just divide by two.
I agree with what you said, but id be ok accepting that a boxer turns his torso, and thus his shoulder-length-from-spine into a punch.
What drives me nuts is when someone says that a fighter has a 14” reach advantage, and casuals think that each arm is 14” longer than the other guy’s.
No, he is dealing with a maximum of seven inches, and thats only if you accept my shoulder turn theory. its likely more like 5 per arm, if each guy is built sorta similarly.