What is the use case for layers like this?

I’m getting used to splitting out my scene into render layers and am wondering something. In this picture…

#2 is where you tell Blender which layers you actually want to render. But I notice that you actually have to have the same layers selected in #1 for the layer selections in #2 to work.

What is the use case for this? Why, if you have the layers selected in #2, would you ever want to have anything but the layers you set in #2 render? I’m scratching my head, trying to figure out the rationale behind this.

The viewport can use local layers, toggle on the header, which separates them.

Wow – that is a weird feature. Never noticed that button. After messing around with it, I see how it can be used, but…wow! Very strange.

Thanks for the tip!