For me it was a compulsion and an obsession. I haven't been officially diagnosed with OCD, but with alcohol and sugar I can definitely claim obsession and compulsion. I mean in the AA big book it talks about this many times, but not every alcoholic is "diagnosed" OCD - so it may be splitting hairs.
It seems like there is a psychological and physical dysfunction involved for sure.
Callas I think you are right in a way. I'm not a psychiatrist, nor do I claim to have the answers, but I think since alcohol affects the part of the brain responsible for Executive function/impulse control, it delivers that Double Whammy quite effectively.