Curious to know what the contrasts are of the golden days and modern day.
I am curious about the difference as well - my guess is that now it's pretty mainstream so there's no real "group / niche" feeling.
Certainly feel that way about some gaming communities I was in in the early 2000s.
The shortest answer I can give you is that meetups are usually for a niche interest, such as programming. Most of the original user groups were far more general -- anything about microcomputers (my first group, on an island off the coast of Maine, was run by a guy with an Epson QX10 and another guy with an Amiga), or anything about IBM PC or Mac or whatever. So the demos were pretty wide ranging and had more variety. You'd have someone showing a graphics application one month (Arts & Letters) and a software utility the next (Norton Computing).