You put 5000 plus on a ship, send them out to sea for sometimes 60-90 plus days without port of call, and hit a port what do you think they will do to let off steam? Keep in mind most of them worked 16-20 hour days 7 days a week. Being drunk onboard ship {underway or on duty} is not a good idea no indeed as such it is prohibited and by enlarge strictly enforced. But that is not the issue here.
Letting men who worked their tails off have some much deserved R & R drinking beer or even straight whiskey ain't gonna kill them. Our nation survived 200 years plus of such policy without the PC IDIOT's we have today running things or rather for the most part ruining all aspects of the military. Heck my Boot Camp Company Commander a MMC {E-7} came in the night we graduated with a snoot full himself.
The rate of alcohol dependency would still likely be much lower than civilians because of the deployment and time at sea demands. I saw a few have issues but the ratio was low. Maybe 1 in 100. Much better ration than most civilians.
Maybe the Pentagon can arrange a nice Ballet for the troops to attend when hitting port after being out at sea long periods of time. /sarcasm
As for smoking? Most ships at least in the 1970's you were lucky to get in a half a pack a day at sea and that was usually in your off time. I don't encourage the usage of either. I quit recreational usage of drinking and cigarettes quit over two decades ago. But I realize that if you want saints go to a Theology school. Not to say that many on ships do not abstain. But I've had many a shipmate I drank with the night beofre I would still trust with my life the next day. Then again there were some who didn't drink who you couldn't get a bit of work out of much less depend on.
Theology school is where many of the sexual-abusing priests got their start.
When I went in they made us dump our smokes and lightersin basic, that was back in 87 when the new no smoke policy went into effect. They used to let the 18-21 year olds get tanked on post with that 3.2 pistol beer. What a waste that was.
IMO drunks, dopers, and smokers can stay civilians...times are changing and we need all the edge we can get.