Experience Based Training Methods

No matter how good the description, a description is not the experience - take a training style that takes an "experiential" rather than a "descriptive" leaning - simulations are better than lectures. Nothing is going to teach you to swim like getting in the water. I dont think its a coincidence that the best instructors all have some kind of hard contact/sparring backgrounds. Does that make sparring essential?

I think that there is massive benefits to sparring. People use the old chestnut "its not a real fight" which is true as a real fight is all out/scruffy as opposed to back/forth and give/take. But you get good distance awareness, mental/physical conditioning.