The situation you described is asinine. First of all, a post with 100 upvotes should see the light of day, even if 500 don’t like it. Something that recieves a large amount of upvotes and downvotes is controversial, not a bad post or irrelevant. It also assumes there are no moderators to correct things that are truly against what that community wants to see.
For posts that are severly off topic or is against the rules in some way, that is what moderators are for.