In Opera's implementation, the author does not specify the size of the output medium or where page breaks go. The browser will automatically lay out the content it finds room for given the constraints of the device. If there isn't room for all the content, new pages will be created. These can be accessed with PgDn/PgUp, gestures, or by controls added through JavaScript.

True, is possible to split content into pages by way of JS. And JS libraries mean that not everyone have to write that code. But I challenge you to write a script that emulates the kind of layouts we are seeing here: http://people.opera.com/howcome/2011/gcpm/ss Each row is a series of pages from the same article.

PgUp/PgDown in a scrolled view will often cut of text at the top/bottom. In many cases, pages will be more beutiful, and more readable. Of course, if you prefer to use a scrollbar, you will be allowed to. Just set '* { overflow: visible } in your personal style sheet.