This is the main problem of the "Hacker News for [x]" type sites. Lobsters got lots of people interested, but it is itself mostly not interesting to read, because there is very little discussion. Sure, you keep out some noise, but you also keep out what makes hacker news great, and that is the comments from all sorts of people.

All these kind of sites serve is a curated link list, which can be nice, but they don't fell like a community if you see the same dozen people leave ~3 comments per article and can only participate yourself after groveling before the chosen.

While I do think a good community needs some type of gatekeeping, being invite only is not it.