As any soil scientist will tell you, clay soil that dries out like a hard sponge is lacking in organic material. Adding compost and cornmeal will change its consistency to more like that of a chocolate cake, and it may still dry hard but not into a solid, concrete condition except in extreme conditions. It's a matter of mixture. The proper ratio of organic material in soil is mandatory to its life sustaining ability. Malcolm Beck and Howard Garrett have preached this for decades because it is the simple truth. A desert lacks in lush growth. A forest does not. The difference is the organic matter available in the soil.
The best way to teach yourself the difference is to do the experiment yourself. Select an area and add compost, and after two weeks to a month, compare it to the area where no compost was added. And I'm not talking about a long project rototilling it into the soil, etc. I'm talking about simply spreading an inch or two on top of the soil and watering it in. If you work it into the soil so much the better, but it isn't mandatory because the natural process will make it happen anyway.
Kathe