The Federation has a rule against making contact with pre-warp civilizations. While I can sympathize with the notion that such civilizations just be left alone, it seems to me the rule can only work if it’s enforced on everyone. When the Federation is eschewing contact with a pre-warp civilization, what keeps the Klingons, Romulans, Ferengi, Cardassians, Xenkathi, Sheliak, Borg etc. from contacting it?