Small, close communities are communities where the bonds between each participant is much stronger, making it costlier - both in terms of immediately broken relationships, and of backlash from the rest of the group - for people to sever it.
Word gets around, but not necessarily from the right people, and - if bad outcomes are not guaranteed - there is nevertheless a strong incentive for it to fall on deaf ears, stronger than it would be in a less tight-knit community.
That describes lots of communities where abuse is epidemic.