Actually, it's not... Many years ago, there was a company that made what was called a "Hard Card," which was a hard drive and conroller on a bracket that was installed in a computer's expansion slot. The manufacturer (I can't recall the name) actually sent out a technical bulletin referring to a known problem of "stiction," where the drive would refuse to spin up... Their answer was in three steps:
1) Remove Hardcard from system
2) Hold with both hands at chest level, at a 45 degree angle
3) Shake like a ketchup bottle
I'm serious here. Also, certain hard drives, like the Seagate ST-4096 were known to have similar problems. I've given many a hard drive a sharp "whack" with the handle of a screwdriver to get them to spin-up, but if that happens, it's just a matter of time before the drive fails permanantly!
Mark