Just by pure common sense I go with Allen Carr's analogy of the pitcher plant. If you're not familiar with that the idea is that if any given person drank alcohol for long enough they would become an "alcoholic". Why people fall at different rates and why some never reach the bottom is down to a number of things: standing in society, job, family, finances, religion, health, etc. Some people just hate drinking and only have the odd social drink so they don't feel like a pariah.
Even people who society would class as moderate drinkers still have to go to great lengths to do so (drink moderately), whether they admit it or not. They impose 'I don't drink during the week' or 'I don't drink before 7PM' or 'I have one month off drinking per year'. If it's not causing them a problem you have to ask yourself why people set such rules. I read an online journal of a guy who white knuckle through 28 days off not drinking to prove he wasn't an alcoholic! He was proud of his achievements but to an outsider he proved the exact opposite.
So I see it as a slow progression rather than a black or white thing and not down to a disease but down to the fact some people's circumstances mean then ingest more than others. Just because someone doesn't die as what society would claim an alcoholic that doesn't mean they wouldn't have become one in 1, 5, 10, 50, 100, 1000, years.
I think the real acceleration starts once you drink to medicate or to do all the normal things alcohol has robbed you off: ability to relax, socialise, courage, confidence, etc.