Keep in mind that the readers of this and other forums are a very small percentage of fishers. I fished in BC for 40 years, including a bit of river fishing, and had never heard the term flossing prior to starting to read this forum a few years back. I doubt there are 10% of my fishing associates who have ever heard of flossing. Mostly they don't river fish so why should they but they are capable of looking to see what works and copying.
This past summer I introduced a young fellow from the prairies to the joys of flossing sockeye on the Fraser. He opined that the method would probably work on the Chilliwack. When I advised that the technique was not used on most other rivers, being a bright fellow, after a short consideration he observed that there must be some unwritten rules. That is a key observation, you are expecting people to observe unwritten rules.