I don't disagree with you one bit. I think his issue was people saying you can't possibly stop drinking without AA. I agree it is rare, but people have used other spiritual means of achieving the same thing. In the end, I don't think not drinking is the only issue. AA is about living, not just about abstaining from alcohol.
If you read the first portion of chapter 5 in the Gospel of Mark, you will see a nearly identical account of what many of us have experienced in AA.