Business need to measure success. This tells them where to keep pushing and where to lay off. If you're not measuring you're just gambling. But even gamblers are choosing bets based on success likelihood, so that was a bad comparison.
Nowadays "every company is a software company". So how do you measure the success of your software endeavors?
With other departments, it's easy to measure success because the goal is a number. Sales are successful if they're closing N dollars, marketing is successful if you drove N successful conversions.
Some teams are a little less easy, but still the objective is clear, HR is doing well if they suppress salaries without turnover and legal is doing well of they keep senior leadership out of prison (where they belong).
Charles Goodhart likely had scrum in mind when he inked Goodhart's Law in 1975.
Any observed statistical regularity will tend to collapse once pressure is placed upon it for control purposes.
Or as it's often stated
When a measure becomes a target, it ceases to be a good measure.
It becomes tempting to apply anything countable to measure success of product teams. Story points, SLOC (lines of code), commits, deploys, bugs, tickets, etc.
These metrics are, in essence, what you're buying from workers with their salaries.
If the metric is closed deals, then it really doesn't matter how the game was played because those deals have tangible results. (This is why you're paying legal)
But what about when you're buying story points, or lines of code? Your story point metric will quickly become the target, and you will become so rich in story points.
Measuring ICs is as simple as paying attention and taking notes.
Just:
With step 1 and 2 you will quickly identify who is carrying their weight, and who is watching Netflix while occasionally wiggling their mouse. And you can optimize for the former.
And step 3 will provide you with a low-pain means to correct productivity issues.
Obviously you can't do this across an org bigger than a few people, so you hire a proxy (middle management).
This avoids the futile effort of putting a number on your product ICs, and allowing dollars to allocate to successful individuals.