Interesting thread.
Ive been going to AA for almost a decade and there you are the only person who can decide whether or not you are an alcoholic. No-one will offer any diagnosis other than perhaps advising that you listen to the similarities on others and then make a decision whether you fall into the label of alcoholic or not. In this respect i have met once a month drinkers and 24/7 drinkers who all share that label and the program of AA is the same for all of them.
Outside of AA I'm not sure how using the label alcoholic is particularly helpful for the exact same reason as the OP pointed out. Lets say an individual has a drinking problem of whatever degree and goes to get professional help would the quantity of alcohol consumed dictate the treatment? Very much so. A dependent daily drinker would detox, rehab would be advised or inpatient services and thereafter outpatient services. A periodic drinker, which one could label functional, may not need that level of support or therapy and may have several issues to work on whilst they continue their daily routines. On that note a person with diagnosable mental health illness would be treated very differently to a problem drinker without which seems obvious; but if one uses the label alcoholic for all problem drinkers assuming that one glove fits all those people with potentially diagnosable mental illness would suffer immeasurably and do.
I think it is up to each of us to use whatever label we feel comfortable with if we feel we have to use a label. Personally i don't like labels at all, i think everyone on this planet has issues and one of mine is that my default is to turn to alcohol as a coping mechanism so my goal is to continue to grow in terms of developing different coping mechanisms. Its not my only issue though, alcohol didn't raise me, create me or teach me how to live!
As for my previous alcohol consumption i have earned the label alcoholic if i wanted to use it
