This is actually one of the things that many psychologists are dubious about. It's entirely possible that self-labeling as an alcoholic forever makes it harder, not easier, for some people to remain abstinent.
To the extent that it keeps you vigilant and involved in a supportive community, it can be good. But it could also make it harder to get back on the wagon if you have a single drink if you think you're "an alcoholic", and not "a sober person who made a mistake".
Due to the anonymous and heterogeneous nature of AA, good data and studies of its efficacy are very hard to come by, so we have little idea if it's actually better than non-AA or pharmaceutical alternatives.