During development, the test suite and the protype are frequently accessed to settle functionality questions. There is still the problem of managing the development of the prototype. Rob has a point. I keep making the mistake of assuming that people will apply common sense to software engineering. You can do a pretty good job of simulating the surrounding environment, the user interfaces, and all the rest in a language such as Visual Basic without the hassle of making it fit in the real target or working with the real interfaces in real time.
Many excellent organizations use it.
There they develop their ideas, proofs of concepts, and the like with little constraint on resources needed to execute, installation, configuration compatibility, interfaces, usability, etc. Some software developers can function well in both worlds. Some only in one or the other. It is the proven way to reconcile the often conflicting demands of creativity and production products. .