Just my experience:
My AH does not use his functioning capability to continue his denial. He knows he is an alcoholic, he knows it is stealing his health. His remorse and guilt weigh heavy on him, yet he does not choose recovery. If I were to quess why, I would say fear. I say this because since his hospitalization after trying to go cold turkey, seizures, mini strokes, etc. he will not see a doctor for any reason.
And I have no denial either. I know it is progressive, but my experience has been that so far for him the progression has been glacial. I know this can change.
I see his health slide. I can see tell tale signs of liver disease in the colour and shaping of his fingernails. I see the unhealthy skin tone he has and I know his bowels worry him. He weight drops and soon he won't fit adult clothes.
I don't think it is less serious. I just know my daily life (and this may change) is not the nightmare I sometimes read on some of these threads, although it can be frustrating and lonely.
I try to not enable in any way and try to work my program.
I do not think he is terminally unique. I know that there are common patterns of behaviours, stages, and similarities in reactions, etc. Where I do sometimes have a little bit of an issue when alcoholics are all painted with the same brush, when it is seems like they are actually describing an abusive person who is also alcoholic.