"No man is an island, entire of itself"
~~ John Donne
This alcoholic never isolated while drinking. Drinking was a team sport. I isolated because of other reasons that ultimately fueled my drinking and drugging.
Being gay, feeling lesser, my childhood abuse, a general feeling of loneliness and being misunderstood drove me to be quiet and unassuming. To never have felt like I could be seen. Not until my 30's did I realize I could be seen.
The odd part is I started drinking at 28. Nothing before that. Then I used drinking to get out and meet people. Expand my horizons.
I think people isolate for many reasons. Drinkers don't have a corner on anything with regard to that. Drinking seems to be just another reinforcing aspect to someone's already isolating nature.
Of course I could be all wrong. And we just want to hide our drinking.