They dont have time to go through chat logs, they have an automated system that will autoban people advertising gold selling sites, and if a player has a problem with the language of another playr in chat, they screenshot it and the GM looks at that.
Barrens chat being shit is a self-feeding meme, people hear about how shit it is and then go and shit it up even more because "that's the way it's supposed to be".
you think it be like it is but it's don't -jack brack