Look at it this way: when you upvote a fitness-related submission, you say "hey, I'm somewhat interested in fitness", when you subscribe to /r/fitness, you say "hey, I'm really interested in fitness."
So, both upvoting and subscribing are actually manual actions.
With which you also say -- or so Reddit believes in its current level of imperfection -- "and I have complete affinity with everyone else who happens to vote in /r/fitness".
Is that true? Is there any subreddit where that is true?
It perplexes me that this is being treated like an either/or. It is not. In reality subreddits see a constantly exploding entropy as users try to fix a broken mechanism of correlation -- the fact that I like gaming doesn't mean that I like the same thing as every other reader of /r/gaming, for instance. Just fix that by splitting off into /r/truegaming, or maybe /r/games, or maybe...
So, the site should be unique for each user, right? But if you take the tactic you mentioned in a previous post: "Give users the ability to dislike something strongly enough that anyone who voted it up is excluded from all vote counts/rankings/recommendations as provided to that user for some period of time." You'll pretty quickly run out of any other users to interact with.
Heavy math/statistical analysis that can be tuned to create a productive enjoyable experience, with the side benefit that it reduces gaming and exploitation.
No. With that I tell Reddit to show me different opinions on fitness coming from people who aren't morons (since the submission was not downvoted). You seem to think that if a person subscribes to /r/fitness, he surely has the same opinions as the hivemind. That's not true at all.
Good subreddits allow all kinds of opinions. And by allow I mean they aren't being downvoted automatically. Of course, there is the hivemind and a dominating opinion, but other opinions are not repressed, that's my point.