Sometime the people you work with are your friends. And sometimes people like to go out with their friends.
Companies that disallow alcohol will have a hardier time attracting employees, as that kind of uptight company doesn't sound like it would be pleasant to work at.
Booze is awesome but there's a time and place for it. If someone gets loaded at work enough to impair their ability to drive, then gets into an accident and injures or kills someone, their employer (in the US at least) could be liable in part. It's one thing to go out with your coworkers after work, or maybe even have a beer over lunch before going back to work, and it's another to need booze on premises.
Having draconian alcohol policies is a negative, and it can be weighed against the pros and cons of working there.
Maybe the pros out weight the singular drawback of uptight HR representives. But maybe it doesn't, and that one negative among many negatives is enough to push someone over the edge of not working there.
Ex:if the pay is higher then maybe I'd still take the job.
I don't really care about employer liability. That is their problem, not mine.
We're all adults, use your best judgement. Companies and offices should be able to have mature conversations around this without it being dictated.
Not many people do coke and ecstacy. Whereas the vast majority of the population drink alcohol to some extend.