Comment by samatman

It's a safe bet that it's more common among jazz musicians than among classical musicians, who have access to the sheet music for practically everything they play.

Probably also more common among jazz musicians than rock musicians, who don't emphasize sheet music and music theory as much (as much, it's certainly more prevalent than outsiders would naively think).

And of course, all these categories blur together. There wasn't any reason to take his post and interpret it in absolutist terms.