They'd have more help if they didn't go around deleting things.
PS: There are already plenty of other wiki's with different focus. There is little need for ex: naruto.wikia.com content on en.wikipedia.com.
And if nobody cares about the article, why does it matter if it's been defaced? And why not delete it once it's been defaced, rather than pre-emptively?
PS: A different option might be to build a custom AI to validate things, but for now balancing Notable around the size of the community seems reasonable.
A walled off wiki simply doesn't allow this type of holistic discovery. And in many cases, the boundaries between subjects can seem rather arbitrary and fuzzy. Where does Naruto end and Feudal Japan start?