"Flagging is meant to be used very selectively for ..."

...then there should be a pop up when someone goes to flag that says "Note: Are you aware that flagging is meant for .... do you still want to flag??".

Many people don't know the "rules?" on HN even if they have been around for some time. For that matter upvotes and downvotes aren't clearly defined. And that whole "in short anything that satisfies ones curiousity" can reach far and wide.

And doing the right thing isn't solely a RTFM either. The "FM" is not really something that people familiarize themselves with or keep on top of. (Commenting and reading HN isn't a job obviously.) If certain behavior needs to be enforced (not saying it does or doesn't) then something has to be in place ad hoc to make it more likely to happen.