I know what you mean, but that is not what I wanted to say.
In most keyframing software you have the ability of regulating the speed curve. The trick is, that when the speed at two points for example 0, and you want to travel a few blocks, the path is not impossible: Instead, between the two points, the camera would slowly speeding up and then down to 0 again. So there is no technical restriction which makes it impossible.
And if I just put more time between the keyframes, I can regulate the speed not as good as I want to. Perhaps I would like to start a path at point A with 0 speed and end at point B with 0 speed (Imagine you drive a car from A to B. Then you do exactly the same) in 4 seconds. At the moment, I would not be able to do so (Ok, I could add a really huge amount of keyframes in between, but that is really not handy).