AGW - lots of good points there. I keep coming back to us wanting to achieve "target group accuracy" when our goal is "first-shot hunting accuracy", where all of those variables will have an effect on that one shot as well when compared to where it hit when the load was developed. I think that "good enough" is about all we can ask for.
Good enough is all you can ever ask for from a hunting rifle - especially when you consider that most shooters are using off the shelf rifles, used rifles, abused rifles, etc.