As the platform currently stands, we have a bit of a “chicken or egg” problem. Too many users browsing by /all can stifle the growth of niche communities, and the lack of niche communities can induce users to browse by /all. I’m not sure the best way to fix this, other than to hope that niche communities manage to grow despite uninclusive behaviour.
Promotion of communities to !newcommunities and !communitypromo, and promotion of those communities to the wider audience