Going back to the start of the thread where you said you didn't understand this:

> this means that using, say, a dictionary means that quite a bit of the implementation gets hard coded into every site that uses the dictionary

You can see you've just said yourself what you were saying you didn't understand - with data structures in C you're responsible for manually managing things that the data structure would via things like generics in most other languages, with you having to instead hard-code them at the use-site to turn the data into something that can be pointed to and managing the lifetime.