Communities definitely have a natural tendency to form around common interests. They also have a natural tendency to fade away. I've been observing community in yoga and around yoga for 6 years now. I've been a member, I've been a "leader", I've even been the common interest for a community. I've seen community build and I've seen community die. I've worked to build community and I've purposefully left communities. One thing all this experience can tell me for certain is that community requires effort. It shouldn't come as a surprise, everything in life does. Effort and practice are the hallmarks of a yoga practice and in turn, life. Bah! you say? I'm a member of communities and they don't require effort! First off, you are a "member", which at the very least requires interaction and communication ... or effort, if you aren't doing those things then you likely aren't a member. Second, if there is more to your community, events, gatherings, classes, facebook pages, email group, pictures, and the list goes on and on, then someone else is putting in even more effort.
Community isn't guaranteed, it definitely isn't a right. Communities aren't there to be controlled or to serve a single person. Community is a natural tendency of people who have something in common, and a willingness to share that commonality together for the benefit of everyone. There is no magic, community only happens with effort.
There is an unspoken rule to community. If people don't communicate or interact then ... well, you can't have a community. The amount of benefit we derive from community isn't always the same as the effort we put into it. For some people its very much the other way around. Still for others it may be equal. There is no hard and fast rule, and sadly many people simply will never understand what community is, nor will they understand that community is there to serve everyone in it. Still a community requires all sorts of people to succeed and roles within a community can and should change over time.
Are you a part of a community you value? How does that community exist? Who does work behind the scenes? How much do you help foster the community?
For a community to succeed the individuals within it must value it enough to put in effort and in some case put the community above their personal interests. There is a natural tendency to split off into smaller groups. There is a natural tendency to be selfish at times and simply take what you want without giving back. However the more you divide, the more you are selfish, the more the community can suffer. There will be people who will choose to simply take advantage of the community without giving back. There is also a natural ebb and flow of people in and out of the community. But the the flow of people in doesn't happen by magic. It only happens when members of the community actively bring new people in, by advertising, by teaching, by being open. Community is not a competition for control or popularity as some people see it. It takes a culture of openness and sharing to make community work.
This is community to me!