Zero Defect, complete process control; is that possible?

Although the old Masters like Deming, Juran and Crosby have been teaching us the same message over and over again (read the book "Quality Is Free" by Philip B. Crosby) it still is an issue that seams to be hard to be convinced about...
Is it possible to have a Zero Defect production system? Is it possible to make your processes completely stable?

Today, in a discussion with highly knowledgable and experienced manufacturing experts I heard this quote:

"There is a balans point where it costs more money to improve the process than it will generate. At that point you have to stop"

Does that mean "Zero Defect" and "fully stable processes" are Utopia?
What is your experience and your opinion??