It's not that I disagree with you entirely, but consider this.
Scenario - you find the target in the binos, then in the scope, align sights on target, check for level. The target takes two steps and stops. You swing a few degrees - now you've gotta check for level again cuz this ain't no runway we're hunting on. If you're lucky, the target is still standing where it was. If you're not lucky, you get to do it all over again. Hunting wild boar, for example, means being able to follow the intended target and taking your shot when the target stops moving; pigs don't stand still for long. Same goes for hunting on a hillside, uphill or down. If you're shooting off sticks or a pod you can't always get enough rotational movement on the rifle to get everything perfectly level and swinging to follow a target means the rifle will inevitably fall off of precise level at some point. My rig wears a level at all times, on the range or in the field. But I rarely find an opportunity to use it effectively in the field.