On the contrary, tmuir's theory of reddit is a fair description of most subreddits (maybe all subreddits) which become popular without having very strict and dedicated moderation.

It does not describe smaller niche subreddits, though, that's true. They still have their own unique personalities.

I think it has a fair claim to be called theory of reddit, because it seems like any subreddit can go downhill in that way if it becomes popular. They converge on a point of mediocrity.