Because this layer is more special which is automatically generated by the CAD alike 0
As long as created dimension before, CAD will automatically create
Defpoints is special not because it is automatically created by cad, but this layer is set to “not print” by default which can’t be changed by setting in the layer manager.
If you careless draw the objects on this layer, when print, these objects will disappear surely. If simply placing some independent objects on this layer, select these objects move to a new layer, then you can printout all the objects. I have seen a user has drawn a lot of objects on the Defpoints layer, and the objects was inserted as blocks or even multiple nested blocks, when printing, most part of the drawing is empty. he is vacant, finally knows the reason, and cost a lot of time to move the objects from the defpoints layer.