Lots of good comments here, and to your original question, it is indeed just another excuse. I too desparately tried to find out why i am an alcoholic. I tried every form of moderation known to man and made some of my own up.
Bottom line, I wanted to know why so I could fix it and start drinking normally again. It was not until I finally accepted that I simply AM an alcoholic that I could move forward and learn how to live my life without alcohol. You don't even need to use the term "alcoholic" if you don't want to, but I feel you do need to accept that there is something unchangeable about you that will never allow you to drink alchol without severe repercussions. And why I am that way is not relevant - I simply am and will always be that way.