Ok, please don't take this the wrong way, parents, as I am not one

Why "protect" your kids from profanity? What's so dangerous about it?
Sure, an ugly language is annoying, but exposing kids to it doesn't automatically lead to bad language. Exposing it as what it might do more good. Kids might use it, but I believe parents have enough authority to ban it in the home.
I mean, they watch violent films, they talk to their friends, who inevitably picks up a few choice words from their pals, and the ride goes on. Discovery Channel introduces them to basically the same mating procedure we humans so much enjoy.
What I am asking, basically, is what use it is to protect yer kids from something they *will* be exposed to by normal social interactions and educational tv?
As I've said, I ain't a parent, and I am quite sure I am missing an important point, which is why I am asking

. Maybe it is the watering down process, i.e it becomes so common that it becomes acceptable in a way, and they use it even at home? Or that it's just plain ugly and you want a zero tolerance towards it, including tv and games etc?
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StSanta
JG54 "Grünherz"