Yeah, what you said sounds good, but it's not true. All cases transfer the force to a certain degree. And when you say, "Single material cases don't absorb much impact," what's your source of info for that statement? It sounds to me like you're guessing without much actual experience or knowledge.
I agree that double layer cases offer more protection if they are properly designed. But a good TPU case offers excellent protection too. I had a pretty basic TPU case on my Droid X for almost 2 years and I dropped it onto concrete and other hard surfaces at least a dozen times. It received absolutely no damage at all. Not even the faintest scratch. It worked perfectly right up until retiring it for the GS3. I currently have at least a dozen different cases for my GS3. Some are hybrids, some are single-layer TPU. I'm currently using a surprisingly thin hybrid case that offers excellent coverage on all sides and fits the phone beautifully. But the other case I use as a change of pace sometimes is TPU and I trust it completely.