If you need to take an item from an array, perform an asynchronous operation with it, and update it in the array, how do you do that safely without messing with indexes, which can change in the meantime? That requires some careful code that would need to be unit-tested.
This is a library for working with identifiable objects in collections, making it easy to access elements by identifiers instead of indexes. The readme goes more into the use-cases and problems with access by index.