Well, not exactly, actually. Because the anonymous attribute created by the capture node is actually stored on the resulting geometry, it can be interpolated properly when the geometry changes, even for topology-changing operations. That’s something an index-based mapping wouldn’t be able to do.
Here’s an example. The capture node stores an anonymous attribute layer with a selection of just the top face. The extrude node then propagates that selection to the side faces of the top face’s extrusion. Then when the anonymous attribute is used later on, it uses the current values of the attribute at that point.
So, transfer by index is the same thing in a lot of situations, but not all of them.
