Think about this: while a girl may discover a cool, new designer on Pintrest and buy a dress from that designer, trust me, she will still scratch out some girl's eyeballs to get the new Louis Vuttion bag. And why? Branding. And hundreds of millions of dollars in marketing to create an image, an illusion, and an object that conveys status. LVMH is the most powerful and profitable luxury conglomerate in the world for a reason (it is about 3x more profitable than Amazon with 20% less revenue).
Brands either die or thrive based on their ability to do two things: create a desirable brand and manage inventory. The entire function of branding and marketing is not going to be replaced by Svpply. Or Pintrest. Or whoever.
Lastly, it's comical you keep mentioning Amazon. One of the biggest reasons for their success is their ability to manage a supply chain better than almost anyone else.