Preserve your technical know-how
If your activity is tech-based and you have no in-house tech resources, then traditional outsourcing is unsuitable. With luck — and a lot of hard work — you'll get the product you wanted. But all the technical and functional know-how accumulated during development is lost.
Yet this know-how is a precious asset; it helps you grow by making new features easier to add, and new members more easily join your development team. It enhances your firm's value in the eyes of investors.
With your dedicated team, this know-how remains your asset.