Why has the staircase been a convenient way for some historians to portray relations between feudal lords?

Why has the staircase been a convenient way for some historians to portray relations between feudal lords? Try to suggest a way to depict these relationships that is not related to the image of the stairs.

Historians use a ladder to explain feudal relations. They depict several categories of feudal lords: from the lowest knights to the king – the main feudal lord. This attitude of people on the basis of property can be depicted through the sphere. In the center, the core is the monarch – the richest landowner, around him is the space belonging to the dukes and earls. They are a little less well off. Even further from the center are the barons. And knights complete the diagram. It is also possible to show feudal relations through a diagram.