Totally agree with your point on the way it affects your life vs. quantity. Everyone has their own story and mine began as a seemingly innocuous social, but fairly heavy drinker in my 20s after I got a job in Houston post-grad UT. Never was much of a drinker before/during my time in Austin, but work happy hours, boozy dinners out with ex-wife and friends, etc. really seemed to "normalize" using alcohol to relieve stress after work. It's pretty much ingrained into the culture in the young professional world- especially inside the loop in Houston. Although I knew I drank too often, it was never much of an issue with my job or any other responsibilities and I was able to get away with it for a few years.
Fast forward a couple of years down the road, and though I wasn't drinking as often as before- somewhere down the line I crossed that irreversible threshold from moderate/heavy drinker to alcoholic. When I would drink "only on the weekends" I was drinking to blackout "en bloc"-style pretty much every single time I picked up one single drink, no matter what my intentions were that night. Once I started, I absolutely had no power to stop even though I knew I was heading for a disastrous night. I woke up countless times full of regret and shame after being told the abhorrent things I said and did the night before- but of course then I'd go do the same thing the very next weekend. I even went short-term cold turkey a few times thinking I was in control and I could "drink like a gentleman." Alcohol laughed at my ignorance and the blackout episodes would rear their ugly head very soon after I picked up a drink again. Rinse and repeat ad nauseum for the next 5 years, until I finally admitted that yes, indeed I do have a disease/allergy and am completely and utterly powerless over alcohol.