When a search engine comes along to your site they’ll see one massive page stuffed with content and not a site comprised of more than one page. While you can write a clever description for your page and use title tags, alt tags and every other trick out of the SEO handbook a search engine will still be indexing just one page: it’s a relatively fruitless effort.
I’ve developed a couple of single page websites and agree they’re not completely useless. A single page site for a marketing site for a single product or sole purpose is an excellent way to engage your visitors, people love gimmicks like parallax backgrounds, bright full-screen background images/colours and flying typography.
The argument people seem to love using whenever the merits of a single page design are debated is that Nike used a single page parallax style layout for their “Better World” campaign and many attribute the rise of the single layout site to Nike. While it’s true they did, Nike are a massive brand with copious amounts of reach, people already know who they are, they aren’t fighting for traffic and attention.
Unless you’re a massive national corporation like Nike, Coke, Pepsi or McDonald’s a single page website isn’t going to do much for you, it could ruin your business if you rely on search engine traffic. The differentiating factor however is if you’re using a single page website to market something super-specific like a product or service then it’s more than fine to have a beautiful single page layout, if you are a mechanic or online clothing store that relies on search engine reach to get new customers, reconsider.