Something like more karma for participation in "Show HN" thread (and a karma cost for contributing to political posts)? Because it is true that right now it is easy to forget that every HN users have some unstated duty to contribute feedback to shown projects.
Just thinking out oud, but wouldn't it be useful if users also had some "field-of-interest/expertise" that ShowHN submitters could tag in their projects, that would somehow draw the attention of those potentially interrested in it? Because personnaly, one of the things that prevent me from browsing ShowHN more often is that most of the time I don't feel that I have anything of value to contribute ("Meh, your new javascript framework to automatize lense composition for svelte in amazon-lambda looks nice, but I noticed that typo in your homepage").