The OP doesn't talk about though. This topic is about extending the headshot hitbox to the neck, which would be stupid, because there is no brain in the horse neck and the respiratory and circulatory systems are based in the chest, not the neck.
I don't think that would impede my circulatory system as much as you think, but my point was that shots to the heart and lungs don't do extra damage, so it's senseless to make their peripheries do extra damage.