I would take issue issue with the word "clearly", as there is controversy, at least according to Wikipedia (which you referenced). Perhaps "arguably" is a better word.
https://en.wikipedia.org/wiki/Twelve-step_program#Effectiven...
> It would be an error to assume the effectiveness of twelve-step methods at treating problems in one domain translates to all or to another domain, therefore readers are directed to relevant sections in each group's article.
[2] https://en.wikipedia.org/wiki/Effectiveness_of_Alcoholics_An...
> While newer studies have suggested an association between AA attendance and increased abstinence or other positive outcomes, older studies and studies done outside of the United States have not
Things like cognitive behavioral therapy and other methods.
Every therapist learns about it.
Nothing is 100% effective on every person. But on large groups it has statistically positive impacts on study vs control groups.
I don't know that there's convincing evidence that medically-certified talking is any more effective than any other talking (if that talking is without significant ulterior motive.) There is, however, evidence that talking about your problems helps. Therefore there is a case to be made that getting people talking about their issues is more important than the qualifications of the people they talk about those issues to. Hell, in 12-step programs and other support groups, people with similar problems just talking to each other clearly helps.