I think types are a bit mediocre as documentation. But as you say, mediocre correct documentation beats the pants off of any sort of incorrect documentation.

Moreover, it's documentation that's immediately available for the expression I just assembled at the repl!

None of which is to say most of us wouldn't love some good, correct documentation. But that takes a lot of effort, and I can see why priorities wind up being elsewhere given that it's a smaller improvement over what's available free than in other languages.

Worked examples are actually low-hanging fruit that we really should be making available, given that we can mechanically ensure correctness. Come to think of it, I wonder if this could just be a matter of surfacing existing end-to-end tests somewhere visible.