Using a flashlight as the primary head light or "only" light is patently ridiculous.
The purpose of this statement was to demonstrate my opinion of trying to use lighting equipment incorrectly.
My experience suggests that typical flashlights are not good at providing a large enough field of light. I guess using two or more flashlights could provide acceptable performance.
After years and years of watching forum threads produce discussions about the benefits and usage of
a single bicycle lighting product - I began to describe to readers the necessity of using at least two lighting sources for truly safe night time cycling.
As the posts above reveal, everyone has their own ideas and opinions - I hope my post shed a little better light on the OP's original - yet terribly flawed comment.