When I first saw such a turntable, the arrangement of the belt struck me first, and I admit not particularly considering the motors. Now that the question has been properly framed, I don't really understand the principle of three motors, but I do get the belt arrangement. It does have something in common with an idler in that it mandates a smaller contact area with the platter, or footprint. This may in turn alleviate belt creep to some degree, and I have come to believe that belt creep affects micro dynamics by smearing the music at a subtle level. It is one workaround, but other belt drive makers have other ways of accomplishing the task.
A notable example is the Artemis Labs turntable that Frank Schroeder designed. It uses a spring loaded pulley to help control belt creep, and at the same time it serves as a noise canceling device of sorts. A less sophisticated solution was found on the 1962 Rek-O-Kut Rondine 2. Yet another solution can be found in the Spiral Groove turntable. Its drive is configured in an optimal way that helps isolate noise and reduces the effect of creep by various positioning maneuvers.
It has occurred to me that a single motor with two equidistant pulleys might be an improvement over traditional schemes, but I build idler turntables, so I'm not a candidate to try the idea. However, a lot of you have belt drives, and are handy enough to make the modification. If one of you actually does, it may be something interesting to others.
