I don't know author's real meaning, but you may be reading too much into "superpower." I took it as: she doesn't drink so much to be dependent / alcoholic, but

I don't know author's real meaning, but you may be reading too much into "superpower." I took it as: she doesn't drink so much to be dependent / alcoholic, but enough that it's fucking with her life (bad experiences, body damage, gateway to smoking again, etc). And she seems convinced that it'd be easy to give up. So that's the superpower: to be able to so easily erase negatives in her life. It's like: I have alcoholic friends trying to give up drinking, and it's very difficult for them, meanwhile it's trivially easy for me not to drink (in fact, my body mostly dislikes alcohol.) From my friends' POV, I have a superpower they wish they possessed.