A good lifter will descend faster than a similar object that is free falling (gravity doesn't have a speed, it's a force that applies a constant acceleration) because they continue pulling on the bar until they are underneath it. In that split second when the lifter's feet are off the ground, they are no longer exerting any upward force on themselves or the barbell but are continuing to pull as hard as they can which translates to a downward force on the body relative to the barbell. Ideally this is happening as the barbell reaches its maximum height, so that the lifter is already underneath the bar before it begins to fall again. Which is why some coaches are adamantly against pulling for too long, as then you aren't pulling yourself under the bar until it has already started coming back down at which point it simply becomes a race between you and the bar as to who can hit the bottom position first, and it's much harder to pull yourself under a falling object than it is an object that is still rising. This is where timing can come into play.
This may also be why tork is against drop snatches (and why I may agree with him, despite having done them in the past). Speed under the bar doesn't come from dropping as fast as possible, it comes from actively pulling on the bar, and you don't get that doing a drop snatch. One could make the argument that the exercise helps reinforce stability in the bottom position of the snatch, which I guess it does, but if that's the goal you're probably better off doing a snatch balance (more of a behind the neck snatch grip push jerk that you ride down into a full overhead squat) as you can use heavier loads. Maybe it could be helpful in teaching someone to relax their legs as they're descending under the bar, but practicing that without simultaneously practicing the timing of that relaxation that comes with the reversal of the body's momentum when performing a regular snatch is of minimal utility, I'd say.
As a final note, I know someone who tells people he's teaching the lifts to that they need to "be fast." I disagree with this. I am more a proponent of "smooth is fast" and "be quick, but never in a hurry" (and those are applicable to other athletic pursuits as well). Speed will come if you do the lift properly, hitting the correct positions and continuing to pull all the way into the rack position. If you try to "be fast" you are much more likely to fuck something up.
Speaking of fucking things up, hopefully that rant makes sense.