Sit down with your co-workers for a beer and everybody smiles. They even make tv shows about it. But sit down with your co-workers for a little opium and everybody gets their panties in a twist.

Fuck my bigot coworkers.
I avoid working with them.

In my restaraunt experience, those parties worked because it was organic. Part of it is that you're probably working nights and weekends, making it harder to socialize with people outside your industry or similar CS professions. Part of it is overlap in demographic, probably being under 25, in school or recent graduate, from the same town or 2, and have similar incomes, which dictates affordability of activities.

Moving into a regular office environment means your off-hours are the same as the rest of the working population. All different incomes, ages, kid counts, living locations, etc. At my job, the core department has pretty good overlap and after-hours things are generally organized by department heads. They recognize the cohesion. But sometimes, HR takes a crack at a company-wide gig and it's awkward. Not drastically, as it's only about 70 people, but we fall into the preexisting groups, mostly based on department. It's fine when it's the Christmas party during normal hours, but it just doesn't work when it's a bar after hours.

But consuming beer is within the parameters of the law inexplicably (in most jurisdictions, as allowed by age).