Traditional art is better for learning. Digital instills alot of bad habits, for example compulsive Undo'ing. While the capabilities of digital art are vast, for beginner it can be stifling.
Given traditional materials, the artist can master the tools and get to creating faster because a pencil in hand is more intuitive. Viewers looking at an artwork understand how a line art sketch was made and such knowledge allows for greater appreciation.
For learning purposes, traditional works perfectly well, paper and pen is much cheaper than tablet, drawing program and computer.