Hooray! I appreciate skepticism! That said, who ever originally wrote this is not wrong, per se. The BG does have two loops a direct (for initiating voluntary movement) and indirect (for inhibiting involuntary movements). Why does it have two loops? Because movement is incredibly complicated and it needs them both for precise control. Another way to think about it is the direct loop is for gross movement while the indirect is for fine tuning that movement into something precise. (e.g., scaling the movement in our fingers to hit the correct keys on the keyboard). He missed somethings, some rather important things that could have helped his argument. For instance, the (1) direct and indirect loops have different dopamine receptor types, (2) there's a change in the ratio of those receptors that happens right about the time stuttering first appears, (3) case studies of pharmacologic interventions in stuttering suggest that dopamine (and by extension the basal ganglia) plays a role in stuttering. There is a review article by Alm (Journal of Fluency Disorders, 2004) that you might be interested in reading. It touches on a lot of these and more. It's by no means comprehensive. But it's an intriguing start.