about 10 years ago... or so..... PERB had series of PA (Perbert Anonymous) meetings.
First meeting had just 3 participants .... last #10 close to 100. We took over The Drake that night.
It was always fun..... you still can find some historical posts.... just search for "PA minutes".
PA meetings were always held in a public spaces so it was just an open invitation posted to all who read PERB.... posters or not.
Later meetings went into more private format, but most of the boards have ( or had ) them ( at one time, I was at the meeting organized by a board in Seattle.... they rented a whole ballroom in a downtown hotel. )
So, yes it is possible, yes it is great fun..... but yes.... it has to be ORGANIZED.
ps... and one other thing..... people who know themselves in person.... usually fight less online. PA meetings ( and recently VCA meetings that some people already mentioned ) had a magical way of making friends
I still, to this day, am in contact with at least 5 people from the days of PA meetings.