From an user pov I don't get the concept behind having a closed network in order to obtain quality content. As an user, if I want to read high quality stuff I

From an user pov I don't get the concept behind having a closed network in order to obtain quality content. As an user, if I want to read high quality stuff I go here on HN, or to specific sub reddits: news aggregators are solving the problem of quality for me. Instead it seems that the idea of having a closed network helps more to solve the problem of bloggers to have a quality, like-minded, audience.