That is because traders are trying to predict things mathematically and the market is more dynamic than mathematical. IMO a trader is better to focus on market pressures acting on the market and seen as they are formed by reading bar by bar. Math is viable in a few circumstances simply because of human behavior patterns but overall, it is very difficult to predict the markets using only math. Just too many variables enter into the equation. Some known, others unknown, some unknown until they happen, other that cannot be known, others not yet see seen, contemplated, or invented.
OP is a professional writer who trades hopelessly, or he is a successful trader who writes about scat SR things but hides some vital trading tactics. Anyway, he has declared that he is trying to piss people off / irritate people.
I wouldn't say hindsight charts are worthless. Well, you did say almost worthless. They are useful for explaining and showing concepts for traders to think about and test on their own but they are much more powerful if they can be accompanied by some live trading examples even if done on a live SIM and better yet if done on a live account. I would never fear ever ever fear anyone copying my trades. I would love them to do so. It would make my trades to be even more accurate! Think about it!
To a large degree what you say has some merit. however, price patterns do show market pressures and inertia.
TA effects price if enough people believe in it then it becomes self fulfilling and effects price. Although its debatable if it effects prices by enough to make a large enough profit from it, to make it worthwhile trading after taking into account the failed signals.