I always see people talking about "don't puncture the organs" when gutting animals, but isn't that exactly what you're doing if you're spearing it through the side? wouldn't it make the meat spoil quicker?
edit: was referring to fishing in particular
You don't need the contents of the digestive system splashed all over the meat.
In fish, besides half digested foods, you will find intestinal parasites.
We always speared fish at the head end from up above the fish with less risk of cutting the gut. Bigger target, too.
Inside a land animal, the chest cavity is separated from the abdominal cavity by the diaphragm muscle layer.
Spear them in the chest to damage the heart and lungs as much as possible and you got the critter on the ground.
Anywhere lower and you risk spilling near-poop onto the meat.