By the way, did you know Stephan Grappelli learned how to play piano by being hired in cafes, cabarets and cinemas (to accompany silent movies),... to play piano.
No, I didn't know that....I guess it shouldn't be a surprise, since you probably figured out my opinion that a "musician is a musician," and the rest is just a matter of specialization.
So, there's Brahms and his early dance hall days, and Grappelli. Probably a bunch more examples out there!
/* edit And why I'm gratified that many others agree with me that becoming an adept sight-reader, who reads anything and everything is one part of the royal road, while recognizing that, no, it's not the whole answer.
But it's a magnificent start, especially if one has a solid foundation (or is working toward that aim) and is aware of basic ideas of fingering, and identifying what one must know to perform and interpret at a basic professional level, if not at the level of a conservatory student.
I suppose someone might say "quality not quantity," but I don't think there is any substitute for reading and performing as much as possible: eventually, one must get the technique straightened out, but why not do what one can at the beginning stages? Hundreds or thousands of pieces, at the minimum, across all kinds of styles of representation in standard notation or even chord/lead sheets, recognition of patterns at a glance, basic professional tools when it comes to performing at the drop of a hat, which also requires a kind of functional, if rudimentary, technical facility. All at one's fingertips, really.
The only other element at a beginning stage is sing every line. Away from the keyboard, or, alternatively, on a different instrument entirely, including the voice. And writing lines and voices: basic musicianship.
A practical solution, I find or have found.
Think about it this way: you want to be a musician, I should think. A very good musician. So, build your toolbox painstakingly and work at it.
Why compare yourself to other mechanics or technicians? Become a great musician. And, yes, work scales and do passage work, but it seems to me as though you'd rather be a good musician. Don't ignore technical or mechanical work, but start with fundamentals, is MHO.*/