I feel that the article highlights an interesting problem, with some good insights. For me, building a productivity app that charges perhaps, $5-$10, may be worth it. But it would have to solve the entire problem, not just one step of their flow diagram. I can't make an app that is good at just editing the document, I should also include the other essential steps the user needs to do once done editing (or before). But this adds to the complexity...

Also, I figured small screen size would be a bigger issue, but that doesn't seem to be the case.