The idea is comparing 2 bullets starting with the same energy/velocity and one creating enough resistance to dump all its energy in the target VS one that passes through and wastes its energy.
We agree on this. My perfect bullet expands to double its diameter and retains weight and ultimately penetrates. If I have to compromise, give me 50% of each. I don't want a bullet that expends all it's energy in the first half of the target either. I want it to get through anything and penetrate bone, muscle or what ever gets in the way at any angle.
A perfect example happened at my camp a few years ago. I loaded the same Barnes Triple Shocks for my 300 Weatherby and my buddy's 308 Win. My bullets penetrate deer and drop them like a stone. Even though they don't run, they are laying in a pool of blood from the nice exit wound. The same exact bullet from my buddy's 308 Win did not penetrate his last buck. It expanded to the same diameter as my bullets. But it ran out of energy and couldn't punch through. It did run, and the blood trail wasn't that great with only one hole. That same bullet, at 600 fps faster, would have mushroomed the same, but hit harder and penetrate.