I'm sure you can hit an 3" circle at 25 yards all day long, the question is, can you hit a MOVING 3" circle all day long? One of the main differences between gun and bow hunting is arrow flight time. In the time it takes an arrow to get there, a deer can move quite a bit, In fact, I've had deer duck when I shot at 25 yards and the arrow missed their body completely- that means they moved their body at least 12 - 14" from the time they heard the shot, to the time the arrow got there.
So it's not just about how good you can shoot. There's a lot of variables when using a bow or xbow, and our job is to try and minimize those variables so we don't wound deer. That's why head or neck shots on a deer with a bow just aren't advisable- it's very likely that the head or neck will move at least a few inches while the arrow is travelling thru the air. Best case, you miss completely, worst case, you injure the deer.