Person 1 adds code that uses this with Pandas. Person 2 sees the csvbase:// URIs and copy/pastes them to use with some other library Foozle that uses URIs and it works because Foozle also happens to use fsspec. Foozle migrates off of fsspec to some other filesystem wrapper. 3 years later, after persons 1 and 2 have left the company, person 3 bumps the version of Foozle the project uses and suddenly tests are failing because they can't resolve csvbase:// URIs, but the Foozle release notes say nothing about removing support for csvbase:// URIs.
The opening of the animation has the phrase “A Mickey Mouse Sound Cartoon” on screen. IANAL but I saw on the news that this means the character’s name and old-style likeness are fair game for new content by anybody.
The most common point is that they're safe to share between threads making parallel algorithms easier to invent, understand, and implement correctly.
You can also safely re-use sub-structures without performing a deep copy. For example, if you want to keep a sub-tree around for later you can do that in O(1) time because it's safe to keep a reference to it. If it is a mutable tree you don't know what's going to happen to it so you need to do a deep copy of the entire sub-tree you're holding on to. This can save a lot on memory allocation and copying depending on your use case.
In a Scrabble AI coding contest I discovered the GADDAG which is like a trie but indexes all of the words forwards and backwards from any starting point within the words.