You can't put a "Only this way works" sticker on a teaching method, because everyone puts a variant on an "approved teaching method" to make it work for them. I use actual paper flash cards. Many people say that using an SRS program like Anki is better, but writing the flash cards makes remembering easier for me. ...
When debating something that ultimately cannot be quantified, the only two courses are the debate goes on endlessly, or an "agree to disagree" resolution is met. Learning isn't something you can quantify, for every person that learned through an "approved" method, there's a crazy person like me that learned some completely other way.
Ok, you're just wrong. Firstly, because you're making a straw-man argument. No one is arguing that one way works and another doesn't. People argue the effectiveness of one vs. another.
Secondly, you're wrong because learning is something you can quantify. First you can quantify whether something is known or not known. True/False. Then you can quantify the time it takes to learn such information. Likewise, I can quantify whether someone at any given point on the planet, and I can give the time it takes to move from one point to another based on different methods.
Any method of learning will work eventually if someone sticks with it, just as any method of moving from one point to another on the planet will work eventually if you stick with it. I can pick a random direction, and walk that way, and eventually I'll cross every point on the planet. I may have to circumnavigate the earth hundreds of thousands of times to do so, but it's still something that can be done--eventually. The point here, is that just because a method will work eventually, doesn't make it a good method. We can quantify the effectiveness of learning methods by the amount of time needed to learn something minus the time taken to re-learn any information that was misrepresented. Likewise, we can quantify the effectiveness of any travel method by how long it takes minus how long it would take if another method were taken. It is not simply a matter of does something work eventually.
In short, when efficiency is the subject of debate, it is not a matter of agree to disagree, or everyone continues to argue endlessly. Since we have a topic that is quantifiable, it is a matter of one group being right, another group being wrong, and another group still trying to understand the argument so they can choose the correct side, and then we have the people that don't really pay attention to the arguments made, or misrepresent the arguments, and arrive at conclusions not supported by any other side.