You are conflating music theory with musical understanding. These two things are separate. For example, many singers know nothing about musical theory, but if you ask them to sing a song in a different key they will do it flawlessly (if they know how to sing in tune). A guitar player can do the same, even because of the shape of the instrument allows this. Maybe this is harder for an instrument like the piano, but it is not a limitation of the player, it is the instrument that requires you to learn about flats and sharps.
Being able to transpose != understanding how transposition works.
I mean sure you can handpick scenarios where some musicians on certain instruments may be able to transpose without knowing any theory. But knowing a bit of theory would unlock the requisite knowledge to do it reliably on any instrument. There is really no reason not to learn some music theory is what I am getting it - it will only make you a more versatile musician.
I'm not saying that learning theory is bad. I love to learn it and I understand that traditional learning is a solid path for most people. What I'm saying is that it is not a prerequisite to play popular music, even in a complex instrument as the piano. Many people have now and in the past learned to play really well without knowing much more that the note names and the basic chord shapes. When it comes to jazz and improvisation, too much music theory will not necessarily make you a good player, and in fact it may hinder you ability to discover by yourself. Improvisation is about feeling the music and interacting with it, it is not about finding the best scale and writing the notes on paper.
I would agree that it is not a prerequisite to play popular music, and music theory will not necessarily make you a good player (theres so much more to it, including feeling as you say, as well as fine motor control).
> Improvisation is about feeling the music and interacting with it, it is not about finding the best scale and writing the notes on paper.
Knowing music theory is not about finding the best scale. It is about being able to talk and write about the building blocks that give rise to musical expressivity in a common language that is communicable to others. In other words, it is descriptive, not prescriptive.
> in fact it may hinder you ability to discover by yourself
As someone who has taken 6 semesters of music theory, and still stumbles upon things that surprise me musically, I would disagree. The difference is when I stumble upon a new sound, I can remember it not only by feeling and how it sounds but also by it's harmonic, rhythmic, melodic, structural characteristics. Which would allow me to use it in greater contexts.
