Are they assuming that the general public are so interested in mattresses that they'll go on the website to check it out, instead of just picking something up at Ikea, or their local discount mattress provider?
They're all identical in how they pitch it too: lots of "science of sleep" factoids and thousands of customer reviews (as if those can't be gamed).
I get the same vibe with them as I do with stuff like Dollar Shave Club; a 'lifestyle brand' that's hoping for an acquisition by an established brand.