You can imagine and tell any story (build any product) you want. The art is rather to build a great story and often leaving things out even if they sound like a good idea makes the story way better.
Here are great insights about how Pixar creates great stories:
Obviously not directly applicable to Product Management but I'm pretty certain that being a great story teller is one of the key skills for Product Management.
"When you're stuck, make a list of what wouldn't happen next. Lots of times the material to get you unstuck will show up."
"I use a trick with co-workers when we’re trying to decide where to eat for lunch and no one has any ideas. I recommend McDonald’s.
An interesting thing happens. Everyone unanimously agrees that we can’t possibly go to McDonald’s, and better lunch suggestions emerge. Magic!"