We all know any number multiplied by zero, no matter how large the number, is still zero. This is true in human systems as well as mathematical ones. In some systems, a failure in one area can negate great effort in all other areas.
As simple multiplication would show, fixing the “zero” often has a much greater effect than does trying to enlarge the other areas.
All Startups need to know that 0 customers is where you start and thus need to focus on growing. Logical, yet often forgotten in a world full of vanity metrics.