Most pop/rock musicians historically have played (and composed) by ear without notation or formal music theory.
It's only in the past 20 years or so that large numbers of pop/rock musicians went to music school.
Even so, virtually all pop/rock is composed by ear today, even for music school graduates. Typically composers start by humming or singing a melody, "transcribe" that to an instrument by ear, and then embellish that further if they know music theory.
You can see from above why most pop music consists of the same 4 chords, with the addition of audience/gatekeeper familiarity (don't mess with a formula that works.)
Most pop/rock musicians historically have played (and composed) by ear without notation or formal music theory.
It's only in the past 20 years or so that large numbers of pop/rock musicians went to music school.
Even so, virtually all pop/rock is composed by ear today, even for music school graduates. Typically composers start by humming or singing a melody, "transcribe" that to an instrument by ear, and then embellish that further if they know music theory.
You can see from above why most pop music consists of the same 4 chords, with the addition of audience/gatekeeper familiarity (don't mess with a formula that works.)