Er, HN already does limit access via arbitrarily-chosen tests of user quality. They just chose different tests. :)
I don't think it'd be a 100% bad idea to implement some sort of knowledge-based testing, wire it up to varying levels of initial access/privs on a site, and see what happens, as an experiment. User privs could then evolve once the user had actually posted or commented or rated things.
I don't think it'd be a 100% bad idea to implement some sort of knowledge-based testing, wire it up to varying levels of initial access/privs on a site, and see what happens, as an experiment. User privs could then evolve once the user had actually posted or commented or rated things.