There is a substantial, not very obvious difference between a developer and a team. Good developer can do many things, and in some cases, one developer can make your entire project work. But, in most cases, it will not be the best job ever done. Good developer can rarely be a good designer.
One developer can not think about your project in a wide scope. One developer has an idea, and everything being done after this is based on his first idea. And this is perfectly fine. If you are ready to accept compromise. If developer is strong enough to battle with all sides of the project.
Most likely, single developer will not enjoy every aspect of the project. He will get unhappy. Tired. Which leads to compromises.
Our developers are happy! Our developers work in team! We always talk about the team, we build things as a team, and never as a single developer. Even if your project is small enough for a single developer, there will still be a team involved in designing, creating and testing of the project. Because we know this is the right way to do it. And we keep our developers happy. Which leads to the best, and only best results you can get.