There is a karma threshold (iirc, I know there is one for downvotes) to be able to flag and a link threshold that if you don't know where to find it, you won't

There is a karma threshold (iirc, I know there is one for downvotes) to be able to flag and a link threshold that if you don't know where to find it, you won't use it. only the experienced HN people will 1. care enough to use it and 2. have the karma for(old members) it so it's a low pass filter of sorts against poor commenting.