[yummyfajitas]

Reddit is a site with an incredible amount of diversity. You simultaneously have subreddits like /r/TwoXChromosomes/ and /r/pua (they hate each other) on the same website. Electing moderators plus entryism will kill this diversity - a large subreddit can direct it's members enter a smaller conflicting one and vote for moderators who will kill it.

http://en.wikipedia.org/wiki/Entryism

Exit/competition is a better mechanism. If you don't like /r/atheism you can create /r/atheismplus.