Layered Objects

Once sent to Layout, an object is manipulated around its pivot point, rather than the individual points, edges or polygons. The pivot point is situated at the center of Modeler space, called the Origin. The Origin is shown in Modeler with thicker grid lines than normal and objects can be moved to the origin using the Center All... function (F2)

Once you have multiple layers in an Object it can be important to differentiate between them. Those other layers might just be tools used for cutting or measuring and thus do not need to appear in Layout. It may be that you have several elements that need to be animated separately (a door in the same layer as walls cannot open and close. It needs to be in its own layer to have its own pivot to do so), and once you do have several layers, how to keep track of them? A multi-layered object will just be named "Object: Layer 1, Layer 2, Layer 3, etc." by default. The answer to both of these issues lies in the Layers Panel (F7).

It is certainly true that in certain instances, positioning elements where they should be in layers in Modeler can be seen as more simple, but there are two main problems. Taking a simple example:

This is why it is important to do positioning and rotation in Layout and leave the chair (in this example) at 0, 0, 0.

The second problem is re-use of the chair model for use in a different house. If it is just a layer in another object, it won't be easy to find again. Better would be to leave the chair in a separate object, that way it can be easily reused in other scenes.