While I do understand what Ong is trying to get at, in his "The Writer's Audience is Always A Fiction", I am not sure that I agree with him. He says that oratory story telling is a much more straightforward type of writing because the audience is in full presence at the time of the delivery. While I see his point I am not sure that I agree. I think messages, even delivered orally, are perceived differently by everyone. The listeners of oratory stories still apply their previous beliefs and experiences when interpreting the message of a given story or speech. I don't think that their being present in body means that the audience will interpret anything as a single unit. There will always be previous knowledge of listeners that will affect how they interpret a message and what they choose to take away from it.
I also disagree with Ong's message about writers writing for a given "imagined" audience. Maybe Ong chose to write for a specific audience, because he wrote academic pieces and wrote to teach, but this is not the case for all writers. To use Ong's own example, he introduces how Hemmingway successfully involved readers by saying "that mountain" instead of "the mountain", so that readers would feel as if they already had a relationship with"that mountain"- they had already been there, they already knew these specific mountains Hemmingway spoke of. Ironically enough, Hemmingway probably didn't write "that mountain" for the readers to understand better. He probably did it because he knew the mountain he wrote of, and it came naturally to say "that mountain". I don't think that a novelist like Hemmingway wrote his novels in such a way that audiences would understand him better. I think he wrote novels as a creative outlet, as a way to tell the stories that lingered in his mind. Ong assumes that all writers write for readers, and that their primary goal is to be understood. I don't think all writers write for this purpose.