People aren't as entertaining as they think they are when they're drinking, and not being drunk means you really need other aspects of the experience to fill in.
You also have the problem that people get suspicious of people hanging around not drinking alcohol.
I'm not making the claim that drunk people are equally fun for a sober person to hang out with as other sober people, which you seem to be responding to - I'm saying the majority of the population would expect there to be alcohol at a party (even the type of upper class New York party described in the linked article).
It sounds like they wanted a hobby meetup group or similar.
> You also have the problem that people get suspicious of people hanging around not drinking alcohol.
Once you're out of college I think this is mostly in your imagination. Nobody will judge you for drinking water or diet soda and you similarly shouldn't judge someone for enjoying a beer at a social event.
You also have the problem that people get suspicious of people hanging around not drinking alcohol.