"Designed to perform closely to Harman"?

Like the DT 990 pro and the 1770 pro and the HEDDphone or the Neumann NDH20/30? Because they are so close to Harman, right???

Pro headphones have nothing to do with Harman compliance. They all follow a different "target", which depends on the whim of the engineers.

I think you've missed something in your analysis: Headphones, which actually adhere to the Harman target are few and far between.

It sounds to me as though you give to much credit to "pro" audio manufacturers.