"But there is much evidence that if a child learns to play by reading first, then they are much less likely to master playing by ear - and even composition and improvisation - afterwards."

Sorry, but must disagree. If this is the case, they have been beaten down by academic music schools, but this is by no means an absolute. The study of composition requires note reading to some degree unless you are Woody Guthrie or Irving Berlin. I think even Paul McCartney reads music.

Playing by ear can be achieved at any age. I would like to see that evidence, who it was by, and how it was applied scientifically.