I understand the reasoning.

Just to tell: when I was looking for the component that would write to the 'layers' parameter in the permalink, I automatically looked into the LayerManager, as it seemed the natural place for it. Then I discovered the Service and was convinced, because it seperated 2 concerns. That's also why I thought to seperate the writing of the catalogNodes parameter from the catalog directive.

The question, I think, should be: do want the component to be able to be used without permalink functionality?