How about this as a solution: * Everyone can write comments. * Only moderators can vote on comments * Only moderators can submit articles * The number of moderators is fixed (at say... 1000?) * If a moderator hasn't moderated in the last 3 months, they are removed from the moderator list, opening up a vacancy. * The person that replaces the removed moderator is the commenter with the highest average point score for their comments (ie total points/number of posts), provided they have posted in the last month. It may be necessary to add a minimum total points score as well (say 100 points, and then it's the person with at least 100 points, and the highest average that becomes moderator).
This type of system should ensure that only things that interest people that themselves have been found to have interesting things to say will get voted up. There will still be trolls, but they won't be voted up.