Your point isn't harmful, but I don't agree with it for myself. I used to be addicted to opiods and I absolutely agree with this "once an addict, always an addict" thought because if was prescribed or given those again I would act very differently with them/use them differently then someone who has never used them before or how I would before I ever got into that. Also the hypothetical pipeline between me being prescribed something for a legitimate injury and then turning to hitting up a dealer when I run out is much shorter than before I started and it always will be. I have a similar experience with binge drinking and have seen the cycle of quitting, to "only sometimes" to "back to my old habits" and how quick that goes.

Kudos for OP though, they seem to have a support system and if they feel it doesn't apply to them that's okay, I don't think it does for everyone but it's a good short hand to describe how easy it is to fall back into old habits. It also helps me handle the occasional "slip up" where I fall off the wagon; I fight addiction every day in my eyes and losing the battle on one day shouldn't lead me to feel like I tossed out years of winning.

Now, most of the time I hear that phrase it's from a place of distrust, maybe money went missing and someone points a finger or someone is applying for a job, and that is absolutely puritanical. And you are right, there is a loaded amount of shame that gets tied to drug use and that phrase, so most of the time I hear it outside of anon groups or therapy I tense up.

But anyway, I find it useful because it helped identify patterns for myself and actually address them.