Web design suffers from trends. When something nice or clever or innovative comes along web designers and developers have a horrible tendancy to bend the new technique to everything without regard to whether or not it is appropriate. In the early days of the web it was truly terrible Java applets taking an image and generating a moving water-filled reflection. From there we got the Flash splash-screen, the 3 column layout, the mouseover menu, the mega-menu, and, well, further down the rabbit hole we fell.
Today's design trend is the "single page design" website, usually with some fancy parallax and scrolling effects.
In the right place a single-page parallax site is the ideal - if your typical user's journey is linear and everyone wants the same thing from the website then a long column of information makes sense. That sort of website is a rarity though - few people have a 'typical user' and few users want the same thing from a website. Single page sites suit a start-up with a single product or a small business that needs to emphasise one aspect of what they do, but that's about the limit of where single page sites suit.
The problem with a single page site is that it consolidates everything in to a long list of items. However pretty and clever the aesthetic on top is, a tightly linear information set makes it impossible to give elements equal prominenence - by definition the vertical position of an element dictates it's importance.
A structured website with information separated in to a logical network of pages enables data to be organised in to groups with equal importance. For some website specifications this is vital.