For example, here is a music theory author that recognizes that two are separate, and therefore has two books:

Music Theory - which explicitly does not require nor teach sheet music: https://www.amazon.ca/gp/product/1986061833/

How to read music https://www.amazon.ca/gp/product/1546933301/

I have half a dozen other "music theory" books which in actuality spend 70% of the time on "reading music"; worse, this boring, discouraging, counter-intuitive cluttered part is typically first in the book (which means that interested minds will give up before ever getting to "the good stuff" :( ).

Basically I had to fight uphill battle with majority of professionals to actually learn something interesting and useful and insightful, as opposed to memorize sheet music (or memorize music theory terms without understanding / reasons why). I may one day decide to come back to sheet music, for many valid reasons; but reading sheet music is 100% not needed to discuss music theory - at least for me!

Edit: I noticed you had similar conversations in the past; it seems I had similar needs/perspective/experience as "jeofken" (https://news.ycombinator.com/item?id=25812227).

I'd be eager to continue conversation via email / chat to obtain your further perspective, if you'd be willing:)