****Is it that, they can't get what's in their head to come out of the instrument****
Exactly. They don't feel they have the technical mastery of their instrument (yet) to express the musical concepts that they "hear" in their heads; to translate them from the abstract to the concrete. These guys (most musicians) were/are always striving to grow as instrumentalists; it's a never ending process. That's the part of music and musicianship (the "nuts and bolts") that is seldom understood by the public. "Reputable" professions such as doctor, lawyer, etc. are known to require an incredible amount of study and preparation for many years; not only does it require even more than that to be an accomplished musician, it doesn't ever stop.
Exactly. They don't feel they have the technical mastery of their instrument (yet) to express the musical concepts that they "hear" in their heads; to translate them from the abstract to the concrete. These guys (most musicians) were/are always striving to grow as instrumentalists; it's a never ending process. That's the part of music and musicianship (the "nuts and bolts") that is seldom understood by the public. "Reputable" professions such as doctor, lawyer, etc. are known to require an incredible amount of study and preparation for many years; not only does it require even more than that to be an accomplished musician, it doesn't ever stop.