Great attention grabbing headline, but it ignores the typical user scenarios where PDFs are created. So how is your typical Office worker who is probably using Word going to create this awesome web page? It's simply not realistic to expect that office workers are going to use HTML, and it's been tried for years and years. Nielsen may as well go after Powerpoint next. Same criticisms and human limitations apply. Yes, better formats exist in the ideal, but ignoring the user's real context and limitations goes against the principles of User Centered Design.