5.6.1. The Instance interface:

The method destroy() instructs the container to destroy the instance. The bean instance passed to destroy() should be a dependent scoped bean instance, or...

I think this should be more obvious. E.g. this wouldn't work correctly even though it doesn't violate the spec:

@Dependent
class Bar {
}
class Foo {
  @Inject
  Instance<Bar> instance;
  void ping() {
    instance.destroy(CDI.current().select(Bar.class).get());
  }
}