In my view, a reasonable amount of theoretical knowledge can only help towards better overall playing.
I've owned a bass for some years now, and was quite happy to be self-taught and play from tabs to tell me where my digits should be. As part of an upgrade to a far better instrument, my partner coughed up for some lessons for me. What a revelation these lessons have been. From a small number of visits, covering scales and their practical use, my understanding and enjoyment of the instrument has increased enormously. This is certainly due to a good teacher (thanks Martin!).
The most surprising thing for me is that the lessons and theory have allowed me to play by ear more effectively, which in this case is one of the requirements of the OP?
There are few, if any, things in this life that don't rely on a fair balance of skill, talent and theoretical knowledge. Has anyone learned to drive without lessons and theory?
BTW, I'm ok with 4ths and 5ths, my car has six gears.
Thank you please
RK