I'm not sure that usenet could scale to the degree that reddit has. Part of what reddit does that makes it good(though it's both a blessing and a curse) is that a lot of the curation and moderation is handled by the community via the upvote downvote system. That means that you don't need as much dedicated moderation handling things which at the scale that some of the subreddits operate at is huge.
Maybe I’m old, but isn’t this what Usenet was / is?