What the fence offers in that instance is the ability to control the genetics, disease, and predators on the property, thus making huge bulls and bucks possible.
While the animals in this instance are most likelyvery much 'wild', the other factors that you've mentioned can still be manipulated. The deer still can't get out. By being able to control the deer on the
inside, you've created an unfair advantage.
I've never hunted behind a high fence in my life, so these tens-of- thousands-of-acres ranches may be different, but I just can't get over the 'containment' issue.