[aapi] use cases for description and label reverse relations?

I'm looking at some difference between UIA and the other APIs, and I've gotten to reverse relationships.

IA2 and ATK/AT-SPI have reverse relations for descriptions and labels, where UIA and AXAPI do not. What are the use cases for label_for and description_for? Owns and Controls make sense, but I'm having a hard time thinking of a reason I'd need to go from the label or description to its owner.

Thanks,
Cynthia