The rules are fuzzy which makes following them difficult. At a first glance they are very simple and clear. When one tries to apply them, things become blurry because of "context". Sometimes one is to take every retrace after a supply or demand line break and sometimes one should not but instead stay in and fan - and so on. Still you say that "no filters are necessary". I probably got it all wrong, but it's still my experience of applying the "straight lines".
Several people are still working at it. Some are here, some are elsewhere and some do it in private (like me).
In order to "apply" them, one has to read and study the material. You never did. That's not my problem. ND's experience is much the same. I don't know whether or not she continues to make the effort with struggling traders. If she does, kudos.
To defend people who applied rules and failed. Most successful traders I personally witnessed use fuzzy edges indeed. With many small nuances. Never I saw anybody online sharing a truly profitable and universal (applicable to any market or TF) TA system presented in a way of clear and absolutely mechanical algo "if, then". That's not the fault of TA traders of course, my point is they probably not always realize that they use fuzzy edges and not purely mechanical approach.
What has become obvious to me over the past few years (I'm slow) is what was obvious to the master traders of the past century: it really doesn't make the least difference what "method" one follows if he doesn't have the emotional maturity to trade, i.e., not only to acknowledge when he is wrong but to act on that knowledge as well as recognize when he is right and leave it the hell alone. Losing traders focus on methods and indicators and settings and formulas and so on and on but don't have the emotional maturity to end a trade that's going wrong or take a trade that meets the requirements of his approach: "I saw at the time that my rules (if he had any) said to take the trade but I didn't because (fill in the blank)". This pretty much precludes their ability to let a winning trade develop. And since they can't "cut their losses short and let their profits run", they end up doing the opposite. Can this be laid at the feet of the method or approach or system? No. The wannabee trader doesn't have the emotional maturity to trade in the first place. If he were to trade MAXOs, he'd still fail.
The statements you made and the questions you asked. You did not, for example, know what the SLA was nor what mean reversion was. But if you've found success in other ways, congratulations.
With all respect, I think emotional discipline only makes sense when the method is profitable in the first place with every entry/exit/adjustment rule already in place. Otherwise we deal with fuzzy edge, an art if you wish. Which is OK, but it's extremely difficult to share talent. Hence the problem for newbies: there are not many 100% mechanical profitable edges who's owners would like to share (for obvious reasons). And fuzzy edges are not easy to study for someone not "born" with the appropriate inclination (intuition, ability to "feel" the market, whatever).
If someone was given a proper edge, the recipient couldn't really fail to make money with it. People fail because they are trying to beat the market with all of their lines on their charts that are really just a coin-toss