C doesn't have userland generics or built-in hashmaps, and there are plenty of hash map implementations in libraries out there (glib, apr to name just a few). Yes, they obviously don't have the type safety that generics enable. But the fact that an implementation of a hash map data structure was buggy doesn't mean that all other implementations will be. And, as those of us who used C++ back in the early '00s very painfully remember, generics support and an authoritative implementation don't guarantee you get good generic data structures, either.

Edit: plus, realistically now, the article's criticism revolves around shortcomings of a particular implementation of a hash table. If Hare had generics, and a hash map implementation in the standard library, and that implementation used the same hashing algorithm and made the same assumptions (e.g. no key collisions), all that criticism would still hold. You can find poor implementations of any data structure in any language.