I've started doing this too. The director of the company I work at is non-technical and will semi-regularly come to us expecting that we can build a competitor to Product XYZ in 6 months.
Pointing out that Product XYZ has 3000 employees and has been carving out a niche since 1995, while there are six of us with no knowledge of that market, is usually the only thing that gets him to accept that just because he understands what something does, it doesn't mean he understands what it takes to build it.
Pointing out that Product XYZ has 3000 employees and has been carving out a niche since 1995, while there are six of us with no knowledge of that market, is usually the only thing that gets him to accept that just because he understands what something does, it doesn't mean he understands what it takes to build it.