I think a good example of a site that makes good use of this sort of thing is Wikipedia (the non-mobile version). I love that I can mouse over links and get more information on something, without having to click to its actual page. It pulls down only the information needed, and leaves everything else in place. This makes browsing far more efficient, at least for me. Even on a fast computer with a fast connection, going to a whole new page is jarring, comparatively. Obviously if you need more information than the summary provides, great, go to the new page. But if not, this works great.
Maybe what Wikipedia does isn't what the article is complaining about. But at least I think the article should mention that "page" is not the only meaningful unit of information on the web, or at least it doesn't have to be.