600 yard shots - ethical?
I concur that we, as a community, need to discourage taking game at extreme ranges.
Having acknowledged that, I would also submit that there is a small fraction of hunters whose skills, particularly patience, are up to the task. Couple a .5 MOA rifle with a hunter who knows what the wind can do to his shot and the willingness to wait for the right moment, and it can be done with regularity up to almost 600 yards.
The problem is that estimating the crosswind to better than plus or minus 2mph is extraordinarily difficult. Two miles an hour is enough to move a 300 Winchester Magnum bullet off track by more than five inches at 600 yards. This is enough to move the impact outside the canonical 10" diameter vital zone. That also seriously improves the odds is that the shot is only a wounding shot.
Anyone who tries a shot of this nature without having first done the study and practice is properly branded an unethical hunter. There is no rifle out there that shoots flat enough to get a 400 yard shot into the vital zone of a deer without at least several MOA holdover and frequently similar amounts of wind correction. You don't learn this until you have tried and studied.
Try shooting milk jugs and jackrabbits at those ranges, and count the number of shots needed to hit the first time. Then count the number of times one gets a first round hit for a target at that range in a new location. If the number of first round hits on that size target is less than 80%, then you can count on often merely wounding an animal that can escape to die a painful death or suffer crippling long term consequences.
My hiccup is blanket condemnation -- even though that may be the only way to discourage the inexperienced from doing something stupid.