I wonder if an analysis of this and the comment corpus could quantifiably show shifts in the opinions of the Reddit "hivemind" since the start. Has the Reddit userbase turned more conservative over the years, or is that just my impression?
You will most likely find a shift in the hive mind, but presumably only because Reddit grew from a smaller community with relatively dominant progressive and atheist/agnostic values into something much more mainstream. Reddit 2006 would not reflect mainstream US values and opinions, Reddit 2015 would be much closer. So I'm not sure we can draw any conclusions from the hive mind shift.
While I agree Reddit 2015 does reflect more of the US mainstream, it is still far from being an actual reflection of popular US opinion. Reddit is far more atheist/libertarian than the US mainstream. And I would argue it is right now far more reactionary/right wing as well. It has become very popular among young white males who have unhealthy attitudes towards women due to the abundance of porn and generally retrograde attitudes towards women of Reddit in general (both the users and the site itself.)
Same goes for its attitudes towards race.