When I first started playing guitar, I read tab and played chords. I could read music from all the years of playing the saxophone in school — some of my students do not have an arts program at their school! But I wanted to push my playing. I bought some spiral bound books of music and just started playing what I could (some super tough pieces I still haven’t played!). I am so glad I can read music!!!!!
One of the things I kept hearing over and over was that people like Jimi Hendrix or Eric Clapton never read music and why do they? They understood how music worked, had an incredible ear and drive! They were also obsessive about guitar, the sound, how to play, and how to shape the sound as they wanted it. By definition of superior performance, they were very rare! If everyone played like Hendrix or Clapton, they wouldn’t be guitar gods, would they!
They understood chords, understood what sounded good. They were musically literate without reading music.! That is rare and difficult.
Reading music helps with learning music (pedagogy). Say you see a major chord spelled out on sheet music, it’s repeatable; you can pick up thousands of different pieces of music written on sheet music and find major chords and understand the meaning of it.
Seeing musical relationships. Music theory. In the end, it’s about what we hear but we need to explain what’s going on in the music but it begins with reading music. Understanding how to read rhythm and notation. Stacking up notes and creating chords. How chords move in the music. Is it in a scale? Where should it go? Where did it go? Different type of chords have different types of sounds and functions. Why does something work in one place but not the other. Why does a Neapolitan sixth chord sound so distinct? What is a N6? How is it used? It’s pretty easy to identify when the key of the piece is given… if you read music (it’s pretty distinct by ear, too).
Reading music will let you learn more things about music and often quicker then without being able to read music. You can teach yourself a lot about music by being able to read music (especially classical or jazz).
I find that many people use those examples as a crutch not to learn to read music. It helps to learn music. On some level, it is pattern recognition and on other levels, it’s a journey in time! You can play music written centuries ago and play it similar to how musicians in the age played it! I encourage all students to read music and theory is just part of learning music but it’s important.