When companies are founded, there is normally a single vision that identifies the purpose of the company. A powerful market need. A set of target customers. A compelling value proposition. Things look beautiful on paper.
However, as founders quickly discover, no plan survives contact with reality. Once they start interacting with the market by selling to a few customers here and there, they begin adding requested features, making changes to their value proposition, and adjusting their business model to fit circumstances they encounter.