In an enterprise situation, for example, do "customers" really know if they love the software, or the presentation that sold them the idea, or perhaps they asked for something to be built wrong.
I would suggest that "very few managers have such a good eye for performance" no matter the metric.
Or is your ideal company one that hires 100 programmers to perform the same task and then fire the bottom 95% after a code review? You're assuming the company has already hired all-star talent (accidentally?) and just needs to pay off their demands. What happens when this all-star leaves to balloon across the world - how do you find a replacement?
Moreover, their code may be considered unreadable or even dangerous by less experienced team members, leading to situations when he is considered less capable by the management than actually is.
It seems to me developing systems with loosely coupled components rather than tight, rigid interfaces, and keeping overall size small is the only way for assessing performance of products of individuals. Not an easy way, for sure.
That's OK because it's not necessary.
Management doesn't need an eye for talent. It needs an eye for demonstrated performance.
If Programmer A consistently delivers excellent software in x% of the time of Programmers B thru G, the users/customers love it, and the maintenance costs are a small % (if they have a way of measuring this), then what the f*&#%@ else does management need to know? Treat Programmer A appropriately or lose him/her.
Talent is in the eye of the beholder.
Demonstrated performance is on the bottom line.