If you have a product that is possible to launch in just a couple months, then you might be able to get by as this guy did. If your product is much more complicated and takes several years for a solo developer to build, then you have to pick the CEO or CTO role and go with it.
My own project has been a work in progress for several years now. I can build it, but my sales and marketing talents are quite lacking. It is a new kind of data management system and it can be really tough to raise awareness and get people to try it out.