Here’s the problem:
When working on very large swimlane diagrams, it’s very easy to not know which swimlane you’re on unless you scroll over to see the title. Sure, you could manually select each item in that swimlane and apply shape data, but that too is also tedious.
Solution:
If =CONTAINEDBY provided the actual name of that shape’s swimlane, you could easily apply a Text Badge (as one example) to ALL the shapes dynamically based on the name of the swimlane. Then, as you are neck deep in some crazy diagram, you already know where you are instead of realizing you’ve been adding shapes to the wrong lanes the whole time.