There is an interesting balance to be struck when organizing social spaces. Social spaces having a shared culture is important, and is trivial in the beginning:

There is an interesting balance to be struck when organizing social spaces. Social spaces having a shared culture is important, and is trivial in the beginning: chances are whatever group formed the space in the first place shared some common ground. From there, in the early stages of growth, the space has a sufficient momentum that the gradual influx of users adapt to the culture, and the culture adapts to the user, and the culture endures. That process breaks down, however, when the influx of new members begins to outpace the normalization between the new members and existing members, accelerating until the desirability of being in the space is eroded, typically due to the very breakdown of the culture of the space. But not allowing new users at all is not an acceptable state of affairs, because that leads to its own problems: one, it guarantees the demise of the space, because people can always leave, but are never replaced, and two, it leads to a radicalization of the group, as fringe elements of the group have a tendency to drive out existing members, leaving only the radicals (note, I mean radical relative to the selective pressure of the space, as most spaces are radical in their own way relative to society at large). Maintaining this balance is thus rooted in 1) streamlining the normalization between the cultures of the space and of new users and 2) limiting the rate of new members. Different spaces go about controlling those factors in different ways: fraternities at universities are a good example: they accept a limited number of members a year, and have a formalized initiation process to become an accepted member of the space. Fraternal orders, like the Masons, the Oddfellows, the Elks and the ilk are a poor example: they over corrected on limiting new membership, until they the damaged the desirability of being in their space until they couldn't recruit anymore. Online, this problem is even harder, as there really aren't any natural limits like there are in life. That means all control factors must be artificial, which becomes contentious.