Even with reference counting, we still have problems. Consider a circular data structure (like a doubly linked list). Even if we just look at the dynamically allocated data structure itself, reference counts are non-zero without any external WhereIs pointing to any node!
This means that even when as lose the last external (named) reference to the data structure, it will not trigger the deallocation. In this case, the nuke method may be useful as it forces the deallocation regardless of the reference count.
Nonetheless, even with nuke nothing is automatic anymore.