I've been drawing this a lot lately when talking to people with software product ideas.

In the picture below, the width of the triangle represents the fidelity and breadth of the product. The height of the triangle represents the reach from the backend to the user. Basically, build a thin slice of functionality that a user can actually use, rather than building out a huge, robust system that can potentially scale, but is not wired to interact with and provide value for the user of the system.

MVP stands for "minimum viable product". In order to determine if a product is viable, a user must be able to use it. Build the thin slice!