Just because a metric is easy to capture doesn’t mean it’s the right metric to use.
It’s like the old adage about the drunk searching for his keys. One night a policeman sees a drunk scouring the ground around a streetlight so he asks the drunk what he is looking for. The drunk says “I lost my keys,” and the policeman, wanting to be helpful, joins in the search. After a few fruitless minutes combing the area, the policeman asks the drunk “are you sure you dropped them here?” “Not sure,” the drunk says, “I have no idea where I dropped them.” “Then why are we searching under the street light?” asks the policeman. “Because that is where the light is,” the drunk replies.