I'm sure I'm stating the obvious, but to me learning the theory is akin to learning the alphabet, phonics, spelling and grammer enabling understanding of what it takes to communicate on a basic or advanced level. I've only ever taught myself enough theory to do just that (basic level for me). It does help to know why certain things sound the way they do, what it takes to sound a certain way which can be consistently repeated.
But in the end, you still have to have something to say. We are talking musically on our instruments be they our own voice or any other thing. Each persons expression/interpretation will be individually unique.
Some of the greatest musicians I've known through my life knew little to no formal theory. There are exceptions to every paradigm though.
I'm sure not criticzing knowledge and application of theory on any level. But it is a tool, albeit a useful one.