It's is just a 12-step cultist mantra used to make you think you need their shitty group that takes credit for the rate of spontaneous remission. The indoctrinated will always mindlessly defend that view. Their minds are lost.
As a member of AA, I agree that it is quite dogmatic and many treat the big book as if it was their bible, Quoran, or the word of God. But it does work for a lot of ppl, I think some ppl need that cult mentality to stay sober. I don;t see why you have such a negative view of it. It seems to be better than the alternatives for many. Just b/c some members seem dogmatic doesn't mean you shouldn't go if you think you have a problem. The only real requirement is a desire to stop drinking (or whatever your vice is). Meetings and going thru the steps help to remind me why I stopped drinking and using other problematic drugs. Everyone is different and there are certain guidelines I'm not following (I'll still use kava/kratom, not going to be celibate my first year, don't think psychedelic use should be considered a relapse, etc.). I don't enjoy pot but if I did I don't think it would cause me to pick up a drink. A few may recover and be able to use responsibly again but I feel most ppl that end up in those meetings wouldn't be capable of that. So why would they help rationalize taking that risk? To be able to walk into a room full of sober ppl that you can really relate to and seeing them laugh/being happy after you recently stopped using b/c you lost so much as a result can have a powerful effect.
There is one story from the big book that comes to mind of an alcoholic who decided to quit drinking b/c it was effecting his work performance. He stayed sober for decades, but as soon as he retired he went back to his old ways and died early as a result.
There are many ways to define addiction and everyone is different, so obviously "once an addict, always an addict" is a generalization. But they don't want you to delude yourself into believing you are an exception that. You may be, but is it worth the risk to find out? Only the person in question can decide if they think it is. It would be irresponsible of a program or counselor to help you rationalize using to find out.

), I've totally seen people who encapsulate that pattern of opioid use (as alien a concept as it is to me