I don't know this for certain, but if you have immutable data structures then zippers are kind of a requirement. Many immutable data structures also have a hashing system built into them that generates a hash based on their content. So, if you have a data structure with a hash, one thing you can do that is convenient is compare just the hashes of two data structures to determine if they are equal. This is much faster than having to parse the entire data structure recursively.

Might be useful for things that are often compared, like for instance the React virtual DOM.