We tell children to don't use profanity because they have a hard time regulating themselves. Telling adults to do the same is misplaced authoritarian behavior, the kind that may come from people who failed to mature and still obey (and repeat) what they were told as a child but now sound obsequious.
Profanity largely exists to be offensive, and loses power when ubiquitous. It especially loses power when five year olds say it for every little mood swing they have.
Nobody wants to hear offensive words from a child because it makes adults realize how childish they sound.
