Hi Nailbreak,
I’m not sure if you are referring to the 3 zones that I mentioned in the article but the center zone I mentioned there would be a side to side zone (not a top to bottom zone) which can help provide firmer support under the heavier parts of the body (hips/pelvis) which tend to sink into a mattress more deeply can help provide better spinal alignment over the course of the night.
The deeper layers of a mattress also provide primary support while the upper layers provide secondary support and pressure relief so they have different functions and changing one won’t necessarily improve the feel or function of the other layers (and in some cases could make things worse). There is more about primary or “deep” support and secondary or “surface” support and their relationship to firmness and pressure relief and the “roles” of different layers in a mattress in post #2 here and in post #4 here that may also be helpful in clarifying the difference between “support” and “pressure relief” and “feel”.
Phoenix