
Gabriel S. answered 05/18/19
Columbia University Music Major
I think Abbate and Parker may have been referring to the earliest stages of Opera that predated Mozart and Beethoven. The first opera's were staged in Florence in the late 1500's by Italian baroque composers such as Caccini and Monteverdi. This was several hundred years before the time of Mozart and Beethoven who were writing in the late 1700's to early 1800's. Given this timeline, Abbate and Parker's statement makes sense as Opera would have started in the late Renaissance and Baroque as an elite art form and gradually became more accessible through the classical era of Mozart with the introduction of new technologies.
These are just some of the first things that come to my mind on this topic. I hope it helps!
Best,
-Gabriel S.