Many years ago, clicking was the simple answer to this question. The general thought was that if you made your page too long, users would only view and read the top half and glance over or ignore the bottom half. Today, things have changed. Many users do scroll to the end of the page and have no problem doing so. Scrolling has become a second-nature and clicking a chore. As user behavior changes over time, designers need to take that into account in their designs.
Anecdotally, I can vouch for this – show me an over-paginated page or other form of UI and I’m far less likely to explore your content than when it’s all organized on a single page. And with non-accurate input methods, such as a touch-screen, clicking can be an even bigger chore, if the site isn’t optimized for touch.