Welcome Steve!!!

I have no doupt that most of todays bows can pass through an animal at over 100yds. But penetration is not the governing factor in not taking these shots.
My MAX on whitetail is 40 yds and I have yet to shoot over 35 yds in over 20 yrs. of bowhunting. The real factors are accuracy, and the possibilty that the animal may move between the time you shoot and the arrow gets to it.

At 70 yds an animal can easily move 15 feet in the time it takes for the arrow (even with the fastes bows) to reach it. Too much of a risk for me.