This does not only apply to people in isolated places. For instance despite living in a large city with an active PM section, I am not part of PM.
Because they hold meetings in a part of the city that is
inconvenient for me to get to, typically at places I don't
enjoy being, at times when it is inconvenient for me to go
there. (I don't drink or smoke and I have asthma. Care to
guess how interested I generally am in going to bars?)
When interesting stuff rolls through town I often
will show up, but since I have not gotten to know people in
the local PM section, I am not that interested in meeting them.
However in a bit under a month the LinuxWorld Expo will be coming to town. I expect that to bring some people from
PerlMonks. Since I actually know people here, I
would be interested in knowing where and when meetings
will take place.