In the right circumstances a one page website can be the ultimate in efficient communication. All the information is on a single page, easy to find and see. The one page 'brochure' style website can be a powerful and clear way to communicate to an audience.
Arguably the most effective way of using a one page website is as a brochure or resumé. The intention is to grab the attention of a potential client by presenting the key information in a manner which creates a visual impact.
Sometimes one page is all you need to provide focus to your message.