Thats not true
Theres no reason why you can't investigate technology independently of actual production. Used to happen in the past: the P.1127 is a good example, the Fairy Delta another. or more recently, the work on the rewinged FBW "unstable" Jaguar (sorry, I can't remember the acronym for it)
Those sort of aircraft all provided technical information as to what was possible - and could be used in a new model
Even the Spitfire was only possible because of the work on the Schneider Trophy aircraft - which were basically pure experiments