Problem with the argument - well, one of them - is that whatever the author sets out to do, readers will always see things differently. Both from the author and each other. To take an example - the author of said article has a Pratchett quote. Now - and this is a somewhat presumptuous statement, but only somewhat - it seems fair to suggest the article author is a Pratchett fan, and given his statements on art, he believes Pratchett is good at getting out of the way.
But I know at least one guy who liked Pratchett but can't read too much at a time due to what he sees as heavy handed moralising. Me, I don't get that, but I do think Pratchett's books are so filled with his character that it's oozing out of the sides. Pratchett doesn't get out of the way of the art, he's there with the reader pointing out all the fun parts.
Therefore, if this is something so out of the artist's control, is it really such a big part of art?
And there's the other problem. I love Pratchett in no small part due to what I've just described. A lot of my other favourite authors have a very strong sense of authorial voice. I don't want my artists to step out of the way. I want them to say "This is my truth, tell me yours". Obviously, subjectively, I don't think them hiding is what art is about. Obviously I'd say that. But trying to be objective, if there are a bunch of people who are the same as me and want the same as me... then should all art be about the artist hiding?
I think Skip has it best when he says anything can be done.
Hmm. Now I'm trying to think of a piece of art I really love where I think the author is hiding.