I can't speak for Doc, but here's my take. There are a TON of folks who are functioning alcoholics - they get up every morning, go to work, pay their bills, and at the end of the day sit down with some beer or whatever. You see this a lot in "bar players" - work all day, and relax by having a few drinks and shooting some pool. Many of the amateur leagues are filled with such players. It's nature and habit for them to have a few drinks while they're shooting.
If you take away be booze - it takes them out of their element, and induces a discomfort zone. The tension increases, and they don't play as well.
Other folks don't really care for the booze, and would rather concentrate on the game itself.
Neither is wrong or right - it's just life. For myself, I fit somewhere in the middle. On league night - I don't drink until after my match - then I have a few with the folks. Same with any tournaments I get into. I'm not a good player by any means, but I keep trying to get better.
Some folks tense up at the word "alcoholic" - it's been given a stigma by society. They get defensive, when really there's no need to. Congrats to you for you long history of sobriety .. it's indeed something to be proud of (especially if drinking is something you crave.)
I don't think Doc intended to "refer" to anyone as an alcoholic, but was just making a general observation from a medical standpoint. .... but I'm just guessing on that part.