For a kidnapping (or for highly targeted attacks) I agree.
However most attacks are run-of-the-mill crap that isn't worth chasing the who.
Imagine a thief has broken into your home and stolen a can of beans. You're nervous and angry. Your spouse will soon be something worse and will probably want you to explain who pulled off the theft, and how.
But only one of these questions, the how, is worth your precious resources; security experts say the who is an emotional distraction.
Do you really care who stole your can of beans, or do you care more about how they broke into your house?
I know which one I'd spend my time looking into