It's rapid prototyping. It might just happen that the prototype is good enough to sell, but once you have a basis, comparisons can begin. If the prototype doesn't have to act as the real product, just a skeleton, it's not so hard to change the "bones" if something isn't working properly.
If the prototype is quickly made, it could even count as part of that upfront design process.
If the prototype is quickly made, it could even count as part of that upfront design process.