Many of the musicians I play with come from the other side of this - they are excellent readers (some unbelievably so), but they can't improvise in many cases, and a great deal of them aren't happy playing unless everything is written out for them; many can't simply learn a riff or parts and the overall structure of the song, and then know when to come in; I've had to score some horn section parts with hundreds of bars of rest for them to count before coming in - something I initially thought they were taking the mickey with - and without this they are just as stuck as me trying to read.
Different schools of music stress different skills, when really all of them should be practiced, as mentioned in the article; while my reading is still BAD, what I have learned has made me a more rounded musician, and also helped me understand what I'm doing from a different angle; in the same way having played lots of styles of guitar-based music means I am much more rounded and capable than if I'd just stuck to one style. However, the author's voice is not one I've heard much in music education; it's still fairly ghetto-ised.