Absolutely true, as it allows all of the components of the vehicle to be loaded and operate normally.
However, when my local dealer tried to locate my drone (after replacing the rear axle), with chassis ears they could not localize it even after multiple tries. The techs that came MBUSA HQ stated that the vibration was inherent to the 3.0 ltr engine design, transmitted down the driveline and is expressed in the rear axle. They referenced a notice like the one that Bob posted, even though my drone is most intense around 2000 and 2800 rpm
Sprinter vans have either ESP or ASR traction system, who will kill the engine control when wheels speeds don't match.
If you want to run rear axle in the air - you need to turn the system off.
That's is what I always do going for smog check, who puts rear axle on the rolls.