There are more similarity between things like Oppia and interactive fiction, I don't see them at odds. It is is wonderful that Oppia has a musical notation interface.
If you zoom out far enough, everything could be considered a quiz.
This will all be on the test.
BUT Oppia has lots of other interaction types: https://github.com/oppia/oppia/tree/develop/extensions/inter...
For example, you can input music notes: https://github.com/oppia/oppia/issues/4842
Or ask the learner to enter a fraction, or to sort some objects.