I was required to attend an AA meeting as part of a school assignment in one of my psych courses. I don't agree with all their steps but it does help people. Alcoholism is an addiction, I wouldn't classify it as a disease in the sense that you have no control over it. However, once addicted it's easy for sober people to relapse and it is a significant mental and physical process to quit drinking.
It might not be the best program, but when I went the people seemed extremely welcoming, helpful, and those attending were getting support with many being sober for many years due to the support they get from AA. If it helps alcoholics quit drinking and turn their lives around I'm all for it.