Why gauge swatching is more important than wraps per inch

I was first introduced to the wraps-per-inch method of measuring of yarn thickness at a workshop in 2003. I loved the workshop, but I was skeptical of this method from the get-go. The instructions for measuring reminded me of Goldilocks and the Three Bears—not too this… not too that… just right. With just right being in the eye of the beholder — via Knitting Daily