Cellular Absorption??
Hi Crab how are you pal?
Cellular Absorption - I have not a clue as to the origin of the title, I first heard of it about 30 years ago. So if it was a joke it seems to have developed into an urban myth.
It is nothing more than the inability to build a ground cushion due to the quality of the surface beneath the helicopter. A rocky surface will do it too and I am sure many more, including long grass. The helicopter will require HOGE power, even in a 5 ft hover.
That's as technical as my explanations get.