The problem with this technique is that it's hard to do in practice against a skilled/experienced person. Nobody skilled is going to attack you unless he senses you are not going to counter.
If he sees you are ready for him, he's only going to attack based on timing. For example say you check his thigh, or check a kick with your lead leg. Your skilled opponent will watch your footwork and see when you put weight on your lead leg (for example when you take a step. At this point he knows you will not be able to lift that leg up in time if he attacks.
THAT's what skilled fighting is about.
This is why in the real world of world class boxing and muay thai, you never see trapping, or this stop hitting taking place. It just doesn't work when two opponents of similar skill levels meet eachother and are constantly thinking in their brain about how the other person is going to react. This is one of those "work on people not as good as you" techniques.
I'm not discrediting the technique for self defense or JKD of course, I'm sure in self defense scenarios there are plenty of times a martial artist will face a less skilled opponent, and can pull moves like this off.