“It works for me” doesn't justify an argument much.
Most of the debaters used evidence to support their claims or refute the other party's. Some interpreted the statistics and methodology used in certain studies and explained why they do not mean the way proponents of dry needling claim. As a massage therapist and writer with a mediocre knowledge of myofascial trigger points and dry needling, this is a great learning opportunity — not just about those two topics but also how clinicians and researchers debate.
Witnessing or experiencing something “works” does not necessarily mean the intervention worked for a particular problem. Sometimes other factors could influence the outcome that has little or nothing to do with the intervention. Yet being humans, we could make mistakes of linking a cause and effect when there may not be any. This is formally known as the post hoc ergo propter hoc fallacy or simply post hoc fallacy.
Sometimes clients or patients get better for many reasons that we may not know. For example, patients with a common cold could get better on their own when the disease runs through its natural course. Some diseases and pain are cyclical, so patients might have painful joints or muscles on certain days, and on some days, they don't have pain. This is an example of regression to the mean, which is the tendency for events to “even out” over time. Thus, patients would get better whether or not they get the intervention.
Patients and clients might feel better after a treatment or remedy, but feeling better does not equate to being better. The placebo effect, temporary change of pain perception, and confirmation bias could confuse them that the treatment “worked.”
Even in exercise science, researchers could overlook other external factors that influence the study's outcome other than the intervention examined in the study. For example, the type of music played in the background, the gender of the observers, and receiving feedback on how to move and execute an exercise can influence the athletes' performance other than commonly measured factors, such as muscle strength and endurance.
Anecdotes and it-works-for-me stories do have some value in science and practice, but remember that they are low quality evidence since they are subjective and highly bias in nature. They should be used as a start of an investigation and inquiries, not a justification for a belief or claim.
In an online discussion or debate, falling on our own stories as our primary source of evidence does not give us a strong and valid support or argument of why an intervention works. But when we use our stories as examples to understand an unfamiliar phenomenon better or to use it to question about something, then our stories have more value to the pursuit of knowledge and critical thinking.