This is the "dark forest" theory of the current internet, ironically posted on Medium [1]. You can put up registration barriers and such, but even being world-readable can attract negative attention. It's getting to the point where you have to "know people" to find cool stuff online.
It's so hard to strike a balance between inclusion and 'eternal september'. Managing a community is incredibly hard work. I don't really know if I can think of a way to be both inclusive and preserve the value of a community indefinitely. It seems that at some point you really need barriers to entry to keep things sane.
I've found that an effective way to strike a balance is to simply refuse to scale. Once people can't access your site only the dedicated will remain.