As well as the sampling bias pointed out by jdpage, the breakage is also the fault of this particular HTML5 presentation framework – it is not necessarily the fault of HTML5 as a whole. The page’s user interface could make it clearer that there are more slides and show you how to go to them – for instance, by showing the invisible buttons along the side on page load. And it’s possible that the JavaScript could be written more compatibly, and have better fallbacks for when the browser doesn’t support certain things.