"The concept is based on the assumption that if you build something that is useful and works well, the users will eventually come to you as result."

Sounds a lot like "Build it and they will come", which has been the death of quite a number of startups. Certainly it's important to build something amazing, but I think you ignore marketing and sales at your own peril. You need someone looking at how a product is perceived in the market, not just how amazing it is.