No, you don't need to, and you are right, it isn't necessary. In fact, I played for a few years before I started doing it myself. But I was not playing as cleanly as I thought I should be, and my teacher recommended that I try it. It was actually quite difficult to get used to at first, but in the end it made a significant improvement in my playing. It was like I had been driving a car with 5 gears, but only using 4 of them.