I've seen this same thing happen with Python's type hints. Turns out giving an "escape hatch" type for devs who have no clue what the type actually is leads to a lot of useless type hints.
Yeah, it's especially bad, when a library doesn't provide type hints itself. It can be comically difficult to find out what the return type of a function is, because every if-else-branch might have a different return value, so you may need to read the function body in full to figure out what the type might be.
Add to that, that lots of the tooling around type hints isn't as fleshed out / useful as it is in fully typed languages and I can definitely understand why someone might not immediately feel like it's a valuable use of their time.