> I do not see it as a gradual linear path as you do,
There were indeed enclosures at Saqqara belonging to the kings of the second dynasty.
The largest of these was Gisr-el-Mudir.
This has also been attributed to Khasekhemwy.
It had hugely thick walls filled with limestone rubble with a skin of dressed limestone.
This building is a 'missing step' in the development towards Djoser's complex.