Sheet Music Isn't Music Theory
Ask someone why they haven't learned music properly and you'll usually hear "I don't know any theory." Ask what they mean and it turns out they mean they can't read the dots. Those are two completely different skills, and neither one is a prerequisite for the other. Conflating them stops a lot of people before they start.
Notation is a recording format
Sheet music is a transcription system. It encodes two things: which note, and for how long. Clefs, key signatures and time signatures all exist to tell you how to read those two. That's it. It is a way of storing a performance on paper, invented because we needed to move music between people before we could record sound.
Look at what's actually written there. Pitches and durations. Nowhere on the page does it say why that phrase feels settled, why the melody wants to fall at the end, or why it would sound completely different over a different chord. The notation records what happened. It does not explain anything.
Theory is the explanation
Music theory is the account of why. Why that chord pulls toward the next one. Why a song can change key and still feel like one song. Why swapping one note turns bright into sad. It is a set of names for patterns that were already there in the sound, and the names are useful because they let you predict and reuse the patterns.
None of that requires notation. You can hold all of it and never read a note — plenty of musicians do.
The proof runs both ways
You have met the first case: someone who reads fluently, plays whatever you put in front of them, and cannot tell you why the piece modulates in the middle. Excellent decoder, no theory. Church and orchestral players are full of them, and they are genuinely good musicians.
The second case is at least as common: someone who hears harmony precisely, knows exactly what that borrowed chord is doing, improvises confidently over changes — and reads slowly, one note at a time. Most working guitarists and a great many producers live here.
Both people exist in large numbers. That is the whole argument. Two skills that come apart this cleanly in practice are not the same skill.
Why the confusion is expensive
Because it makes people defer. They decide that before they can get serious they must sit down with a book of notation, and reading is slow and unrewarding at the start — it is decoding practice, and decoding practice does not sound like music for quite a while. So they stall there, and conclude the problem is talent.
Reading is a genuinely useful skill and it is worth learning. It gets you access to several centuries of written repertoire, it makes you employable in a lot of rooms, and it is the fastest way to learn a piece you cannot yet hear. That is its own payoff, and it is real. It is just not the entry fee for understanding music, and it is not the entry fee for playing.
So which should you do?
Whichever one you actually want. If you want to play the repertoire that exists on paper — classical piano, orchestral parts, choral music — learn to read, and start now; it rewards patience and there is no substitute. That is what this site is for.
If what you want is to work out songs you love and understand how they tick, reading is not the first move and never was. Start by learning to hear, then add the explanation once you have something to explain — which is a question of timing rather than whether.
And if the honest answer is "both, eventually" — fine. Just stop treating one as the gate in front of the other. They are separate doors.