Fads come and go.
But fa-jing has been out there for a long time and utilised by many famous martial artists. The old one-inch punch was the flavour of the day back in the 70's and was glorified and mystified. People would study photos of Bruce Lee using mathematical equations and geometrical calculations to try and gain his secrets, especially that of the one-inch punch. All they needed to do was to have someone tell them about fa-jing which is what all of these people were using to gain such immense power over such short distances. Most people would study the hands of the exponents, claiming that it was this angle or this direction that caused this supernatural power.