I am part of a moderation team somewhere else, and the internals may not be the same but the deal ends up being: sure, players chose to turn off profanity filters, but that does not mean they want to see public profanity.

A lot of people do so for many reasons (silly words that get caught by profanity filters, or maybe they like tossing the occasional profane word in private conversations.)

Basically: you want to use foul language, try to hang out with folk that think the same way and keep that to party/fc chat. Most moderation teams will be VERY strict about language in public/default communication channels.