It made sense to measure performance in what I call physical terms, such as counting lines of code written by programmers in set amounts of time. IBM wanted to share costs based on the amount of code delivered by programmers each month. IBM has evolved, but it never did learn how to develop PC software for the mass market. Neither have the Japanese. Counting lines of code or using another measure that takes complexity into account, like function points, may still be useful sometimes, such as when comparing programmers creating very similar applications.
Physical productivity is almost irrelevant.
This measure, though, also has problems. It penalizes companies with weak marketing and sales organizations or the inability to bundle products. PowerPoint, for example, generated minimal sales before Microsoft introduced Office. Bundling this product with Word and Excel to create Office, which now produces billions of dollars in sales and profits, made the PowerPoint team enormously more productive in terms of sales per programmer. We can't easily measure economic productivity for products that have no price.