IMO it is audiophool bullshit. CDs do not travel at a constant RPM, at least according to this:
Revolutions per minute - Wikipedia, the free encyclopedia
These drives play off the belt drive turntable reputation. Since turntables DO travel at a constant rate of 33 rpm (or 45, etc.), there is merit in the use of a belt drive here. But not so much in a device that must change speeds, which a belt drive is not as good at as direct drive. Some people do swear by them though (CEC is it?).