I don't have to cite anything, because I'm not the one making claims.
Your claim that millions of people claim to have been helped by AA is based on what?
It's probably true that some people have been helped by AA, but how many? One out of 20? Out of 100? Out of 1000?
And of those who claim to have been helped, what evidence is there that a different method might not only have helped them but helped even more people?
Numbers are of no interest to AA; though, of course you can find people to argue with about anything.
AA makes no claims to be the one and only. Some folks will attest that it works for them. Others will have a different story. It’s all good.
Their personal testimonies which have been witnessed by millions and millions. And those making the testimonies don't have to cite anything either because they are talking about their own first hand experience. And it really doesn't matter what the success "rate" is, if you've got an alternative that has produced millions and millions of firsthand advocates over a period of decades I'd be happy to hear it out. If you know of a "different method that may have helped them" they lets hear about it.