If a "dull" broadhead doesn't cut on the way through a pass through shot, then what is is doing, moving things out of the way saying, "ok please move out of the way lungs, please move out of the way heart....ok thank you now I will exit out of the skin...thanks"?
Dull blades will push there way through thus not getting as good of penetration, sharp blades will not push, they will cut and go much deeper. This Is the exact reason why I shoot a cut on contact head Brett. I want my sharp blades cutting there way through, not pushing there way through like a dull head or a bullet/chisel point head will do.