If the spirit of the post is that a couple grains of powder one way or the other isn’t going to change your hunting success much on big game animals under 300 yards its hard to argue.
Thing is; at close range like that nothing much else matters much either. Theres a lot of big game hunting done on on animals that aren’t that big, or that tough, or that far away. As targets go, the vitals are large. Accuracy within reason isn’t particularly important at powder burn ranges like that, wind is just something to keep in your face, trajectory is a non issue , and anything worth closing a bolt on will hit with a pretty good smack. If you swung a dead cat in a gun store you’d knock down several perfectly adequate general purpose big game rifles. It would help if you were close to the bolt actions between 6.5 and 8 mm or so, but much of it could be taken care of using this selection criteria down by the muzzleloaders.
Thing is; once you step out of that seemingly broad; but limited window some things start mattering a little; and eventually everything starts mattering a lot.