I my line of work, knowledge of how filters, porosity, capillaries and water surface tension interact with each other has been a long and heavily studied subject. The theory is frankly over the head of most of my peers, and its something I can only claim to marginally understand.
I'm convinced that the porosity of briar and meerschaum matters. It doesn't surprise me at all, that less dense materials are going to have more pores to both absorb water vapor and provide insulation. Insulation works both ways, in that keeping heat in will prevent a ember from burning out, leading to more effortless smokes, which results in less puffing and subsequent overheating. A bit of a catch 22, that is.
Cake is a filter (as is also the surface of briar/meerschaum/cob). It allows water vapor to pass, but not the tar. It also acts as insulation. But cake can ghost, as it is catching and retaining the heavier volatile organics.
Smoking will heat cure briar, which creates micro fractures/capillaries, and also breaks down residual sap. This will connect more pores, which allows for more water vapor absorption. The pores and capillaries will actually suck the moisture in to them. Wet your finger and put it in a new meerschaum chamber and you can feel the suction occurring.
Engineering and fluid dynamics matter too, in promoting good air flow and keeping the water vapor in suspension until it's in your mouth. That can improve flavor too.