I remember getting a certificate when I was a kid, practiced a lot and never really understood anything. It's all just memorizing.

Now I'm learning scales, chord progressions, chord inversions, music theory and it's a lot of fun. It's also a lot easier to learn new piece when you have some theoretical understanding, it actually made it easier for me to play the guitar also.

I can't do anything unless I really understand what I'm doing, and the classes I used to take keeps these stuff for more 'advanced' players.