If by "power tripper" you mean "person who is using reddit correctly"
The reason there are separate subreddits is to allow niche communities to form, instead of having one monolithic overall community. These communities distinguish themselves with a unique focus, look and policies: what's on- and off-topic there, whether people are expected to behave civilly or can feel free to be brutal, etc.
One issue that arises is that casual, new, or transient visitors to a particular community don't always know the rules that tie it together.
As an example, imagine a /r/swimming and a /r/scuba. People can read about one topic or the other (or subscribe to both). But since scuba divers like to swim, a casual user might start submitting swimming links on /r/scuba. And these stories will probably get upvoted, especially by people who see the links on the reddit front page and don't look closely at where they're posted. If left alone, /r/scuba will just become another /r/swimming and there won't be a place to go to find an uncluttered listing of scuba news.
The fix is for the /r/scuba moderators to remove the offtopic links, and ideally to teach the submitters about the more appropriate /r/swimming subreddit.