One could argue that, from the point-of-view of a reader, Reddit is a clone of Usenet, or Fido, or BBSes. Not the back-ends, of course, but the UIs, the organic growth of communities, the community spirit that often develops, the meta-arguments about policies, moderation, moderators.

The clones that drew the most attention all ended up becoming right-wing cesspools. I remember they were often created because of free-speech absolutism which was code for "I want to express hateful views without consequence".