It would be probably cheaper and much better for the world to set up something like this for Elon, where everything is exactly how he wants it.
General submissions have tons of comments, so there are actual discussions going on, motivating users to check back often. Also (at least for now), the discussions have less noise.
Content-based subreddits (like instantkarma, holdmyfries) where there is minimal discussion can be easily replicated with a bot, until organic submissions reach a critical mass.
That leaves community based subreddits, but when Reddit aggravates the main users they can easily move (like piracy did).