its much more than moving your right hand fast.
You have to silence strings your not fretting(as your right hand will most likley hit an open string).
you still have to know what ever lick\run you plan to shred,so if you cant play the lick\run\scale your obviously not going to be able to shred it.
Skill must be in your left hand to fret the notes.
being able to shred "cleanly" is a huge talent.
Not just anyone can shred,and fewer can make good use of it.
The solo from angel of death(slayer) is a perfect example of what skill is needed to play cleanly yet fast.
They dont put it to good use and rely on it exclusivley,its just a showcase of great technique.
Megadeth used it well and maintained a great amount of feeling and melody.
Try once,fail twice...