There are many factors that go into a dormancy. If I could draw a pie chart, I would put decreased photoperiod as the most dominant factor, at (for sake of argument and numbers) 60%. Then I would put cold temps at 30%. The rest would be virtually no food around and less water.

People do different things, partially because there is more than one legitimate way to approach things, but also because of where they live. If you live, let's say in North Carolina, your VFT can stay outside all year long and it will be cold enough to expereince some freezes. But the plants have adapted to those conditions. If you live in New York State, a VFT may not survive the frequency and intensity of the cold. So there are other approaches, such as a greenhouse or a highly mulched bog or taking a naturally dormant plant ti the fridge for the winter. In a warm climate, a fridge dormancy may be the only way to provide cold. But let's not forget that decreased light is the dominant factor. I believe those in climates that don't naturally see to many frosts ( San Francisco area?) are nevertheless seeing their plant enter dormancy, by a somewhat reduction of temps, but significant decrease in light. Dormancy is confusing because it is both the process and the slow or no growth state. The process actually begins at the close of summer. A frdge pretty much guarantees that there will be slow or no growth - and a deep sleep. But you don't want to toss a 70 degree plant into a 40 degree fridge! In nature, temps waffle in one direction or the other, but photoperiod is curve in one direction or the other.