First, if you have many people you can buy alcohol in bulk much cheaper than usual, if most of your workforce enjoys it then it is cheaper to buy it for everyone than giving increasing salaries a bit for people to drink on the streets which can be expensive. This is especially true for a very young workforce which spends a lot in entertainment.
Second, in startups which are pushing people to work for long periods of time, it can be a way to disguise burnout. If you are spending all day in the office you can feel your social life suffering, but they bring your social life to the office, I have my own anecdotal evidence of this.
Third, to a smaller degree, people will stick around and while they are not exactly on call it can pop up solutions to problems or new ideas to the office, I've seen many TGIFs crazy ideas get implemented and generate a better work environment, it can feel like a much safer meeting space for people to speak up.
They're not mutually exclusive. My office has alcohol, but people only tend to drink around or after 5, and typically quietly at their desk while working on something. Occasionally there will be a few people having a conversation in the kitchen over beers in the late afternoon.
I wouldn't describe it as a frat house though, and I think if you need to use that to describe an office, that's your problem; the alcohol is just a symptom.
I'd be okay with removing the alcohol if my employer also stopped driving me to drink[1].
I'm not a teetotaler, but it just seems unnecessary to me. Start with a culture of "we drink at the bar", and it never has to be a problem for anyone in the first place. Alcohol doesn't make you better at your job, so there's really no argument for it, other than "culture", which goes back to the shibboleth thing....
The prohibition movement was at least partially anti-immigrant. But saying "drink on your own time" is neither prohibitionist, nor anti-immigrant.
...get treatment for your alcoholism.
If you merely want a drink, then...
> finish your work, and go out and enjoy your life.
It's a complicated question. What's innocent, non-coercive fun for a small group of responsible people can get wildly out of control with one bad hire. And we don't do interviews for "angry drunk"....
Having worked at dry offices, offices that had alcohol available at all times, and ones that did weekly TGIFs or whatever, I can't say I favor the trend. Invariably, it becomes a problem, and then people start moaning about how the culture is changing because the alcohol is disappearing. It's also alienating for a lot of otherwise good people (some people are alcoholics!)
It's a workplace, not a frat house. If you need a drink, finish your work, and go out and enjoy your life. But then, I feel the same way about office meals (I'd prefer you just paid me a higher salary, and I'll buy my own food, thanks), so I'm not a "team player".