People add language features because they're easy to do in the implementation they already have, not because they're well-principled.
Concrete example from personal experience:
All objects in Ruby have a unique ID. The standard implementation of Ruby added a function to go from the ID to the object. This was easy on the standard implementation of Ruby, because the ID is just the pointer, so you can just cast it. It's a nightmare on more sophisticated implementations of Ruby where an object may not have a single canonical address that you can use as an ID, and you need to store a huge separate mapping.
Yeah, once you introduce moving garbage collectors that happens. I'm sure ruby isn't the first language to have made that mistake (I believe some implementations of SQL actually have similar, a reference to the row on disk, and it turned out to be a short-term gain and a long-term mistake).
Concrete example from personal experience:
All objects in Ruby have a unique ID. The standard implementation of Ruby added a function to go from the ID to the object. This was easy on the standard implementation of Ruby, because the ID is just the pointer, so you can just cast it. It's a nightmare on more sophisticated implementations of Ruby where an object may not have a single canonical address that you can use as an ID, and you need to store a huge separate mapping.