Balto, I want to ask you about this. I've never seen the Gracie knife defenses, so I can't comment on whether they make sense or not. But I have trained some of the other Gracie self-defense techniques. And yes we trained them in a mostly compliant fashion. But I don't think that training was worthless. First, I was training them with a group of people who were used to sparring with resistance. We were all used to the idea of taking a technique, say a basic armbar from guard, and drilling slowly at first, in an essentially compliant fashion (give me your arm) and troubleshooting all the steps of it and looking at different setups, knowing that our eventual goal was to apply it in rolling. And I think that philosophy carried over to drilling the self-defense techniques, drilling them the same way, even if we never did the final step of applying the technique in sparring because nobody would grab us like that in sparring. Part of it was that everyone had some grappling knowledge, so had a basic sense of how to grab, how to react, and so on. I don't know exactly why, but I've seen similar self-defense techniques drilled in both BJJ and TMA, and even though in neither case was that specific technique going to be used against live resistance, the people in BJJ practiced it in a much more effective fashion. Second, on one or two occasions I have used the self-defense techniques in rolling at least in a modified form (for example, forms of the rear bearhug defense where you reach under and grab the ankle and modified forms of the armbar over the shoulder against a grab) and they did work, against an opponent with some small amount of training. Of course, I don't have the same confidence in them as the techniques that I use every day, but having some technique to go for is better than none.
To summarize: I totally agree with your point that resistant sparring is essential. But I don't know if I agree that there is no point to drilling the self-defense techniques against less resistance. At worst, I can take something from it and it makes me think of how to use grappling techniques in a situation that I don't encounter often in class.