Not all sites are about content. A friend of mine recently struggled with this. He is able to get top quality swords and has a cool selling platform. Problem is that this does him no good on search rankings.
That's an interesting point conceptually: the best result for some purposes might be best for a reason that comes from the offline world. For example, if you want to buy rare things, you want to find the dealer with the best expertise and access to sources of those things. That dealer might have an incredibly minimal web site with almost no content -- maybe just contact information.
The original link-structure analysis idea in PageRank was meant to address issues like this a little bit: if everybody links to that dealer's page, it's a good suggestion that that dealer is important, regardless of the content of the page. But there are also things that people don't talk about on the web that much, or don't link to on the web that much (especially if they relate to a secretive, insular, or otherwise not-heavily-web-using community).
You could say it's no fair expecting search engines to know about social facts they can't possibly observe, but in any case it's a reminder of how complicated the idea of relevance or the best result really is!
This is why a lot of SEO advice tends to be start a blog to run along side the selling platform. Write lots of stuff about quality swords to suck in the search engines. Really this shouldn't be necessary. If you want to buy a sword, ideally the SE would know you are looking for shops and not for info about swords. It would then rank according to customer satisfaction or something.. how it would determine this I'm not sure.
Be a good player. Provide good content that your users care about. Positively add to the Web. Google will find you.