Wrong signals?

Came upon this web design company that goes by the name 37signals. From their home page:

... We give all of our clients personal attention and are proud that 100% of our clients are references...

If all their clients are references, it means that none of their clients came upon their website and decided to hire them by looking at their online portfolio of work.

So if your website isn’t selling your own business, why should I trust my business’ online presence with you? What signals are you sending?