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.
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.