I agree with the sentiment and will add that I sometimes feel the standard library has more of a focus on currency types with minimum API commitments, and that sometimes I would prefer if it would 'get out of my way', so to speak, and provide reusable types with maximal utility for library authors.
One particularly annoying example is IndexingIterator. It has a trivial implementation but no official constructor, so you can't make an iterator over a custom slice of a collection -- instead, you need to make a slice of the collection, and iterate that. It's a subtle difference, but in our type system an iterator over <T> is not always the same as an iterator over <T.SubSequence>.
The result is that you need to DIY this trivial building block, for like... the most annoying of reasons. It just feels like the kind of thing you shouldn't have to do.