The volume of fairly famous or otherwise well-established musicians in rock, funk, and even jazz with a poor or non-existent ability to read or write music nota

The volume of fairly famous or otherwise well-established musicians in rock, funk, and even jazz with a poor or non-existent ability to read or write music notation is not insignificant. Then there are all the non-western scale musicians who learn other systems, or use some variation of solfège to explain musical ideas.