I’m an admin of this site; I work full-time on trying to help people on LessWrong refine the art of human rationality. (Longer bio.)
I generally feel more hopeful about a situation when I understand it better.
Non-disclosure agreements I have signed: Around 2017 I signed an NDA when visiting the London DeepMind offices for lunch, one covering sharing any research secrets, that was required by all guests before we were allowed me access to the building. I do not believe I have ever signed another NDA.
The first two reasons that come to my mind are (1) other instruments have much more career incentive to do so (in that there are many more jobs for classical violinists or violin ensembles than for classical guitarists), and (2) it’s possible to have a much more successful career as a guitarist knowing only chord positions and not having a more detailed understanding of the fretboard, than it is with other instruments where a knowledge of how to play complicated melodies is required.