The author admits that "there are some sorts of documents for which a WYSIWYG word processor is indeed the natural tool. I'm thinking of short, ad hoc, documents which have a high ratio of formatting ``business'' to textual content: flyers, posters, party invitations and the like".
I think that those ad-hoc, one-page documents represent a majority of documents created by users - even if you count the pages, not the complete documents.