If you look at ballistic charts for 00 Buck you see some interesting things. One thing that becomes immediately apparent is that the pellets shed velocity very quickly. Not surprising because a round shape has the worst ballistic coefficients of any shape. That's why they went to other things way back in the day. Now because the velocity drops that in turn effects the down range energy which then effects the ability to penetrate. most charts show that 00 Buck at 70 yards will penetrate about 3 inches. And that my friends means it isn't adequate to cleanly take game. Now a shotgun can be choked to throw pellets in a tight pattern at 70 yards but that doesn't detract the physics of the actual pellet. Science ban be a bummer sometimes. Not saying a perfect shot in the ribs would allow the pellets to get the lungs but throw any bone or dense muscle into the equation and you're talking a different thing.

Additionally you really can't aim buckshot because of the spread. You direct it but you don't aim it. Another thing to consider is that not all the pellets get to the target at the exact same time. They are sort of strung out in a line because they shot column is longer that the diameter of the bore. So if a deer is moving the pellets won't all hit the shoulder area, assuming that is the target. Due to flight time some will hit farther back.

One last comment is that many people simply suck at estimating ranges. My bet is that deer dropping cleanly at "70" yards are probably a lot closer. Go to a football field sometime and stand on the goal line and put something 70 yards away. It's a pretty fair distance especially in the field and most time buckshot is used where the cover is heavier and I've never seen the possibility of a 70 yard shot in heavy cover but admit I haven't hunted everywhere.