That's generally true, I think. Still, comics have always been generally more foul-mouthed than most entertainers - except maybe rock stars. And some have been swearing like troopers for decades.
Take Billy Connolly, who uses the F word almost more than any other in his routines. Interestingly, people very rarely find his swearing offensive. I think that it's because he's got such an affable personality, it doesn't sound mean or aggressive. I'm sure that many people who would usually find profanity offensive give Connolly a pass.