I think in some instances, and they only use the quiz on some of the articles, this is a good way to filter the idiots, but on the negative side I wonder how many people forgot the intelligent thing they had to contribute because they had to spend time and mental energy completing a quiz. I hope this doesn't spread beyond serious things for serious people , it is very poor UX to ask users to jump through hoops and spend time on a quiz before they are allowed to participate.

Surely a red warning text in the textarea element where the comment will be typed out is a better idea? The quiz still doesn't eliminate the need for moderation even though it _may_ have gone some way toward reducing that need.