Most people go to reddit to hear about news or see what's popular, not to sift through new submissions for gems. If reddit cared only about democracy, it would solve the problem of an incredible submission being buried by a measly five to ten downvotes in its first twenty minutes regardless of how many people would have liked it overall. Personally, I have neither the time nor the incentive to try to influence groupthink. (I was very careful in my choice of "groupthink." A democratized frontpage that hundreds of thousands of people influence is almost equivalent to literal groupthink. And that's not terrible in and of itself, but if you're going to argue that mods should be stripped of their tools, then it becomes quite the dilemma.)

HN, on the other hand, seems much truer to the overall thrust of your argument, because there are no downvotes for submissions, and only two upvotes are needed for a story to reach the first or second page of HN. But HN only works because there are exceptionally smart and prudent moderators who are constantly curating the singular frontpage.