i think this is a result of parents just not caring what their children watch as long as it's childish. farting? childish thing; no one bats an eye, because children are meant to watch it and they laugh at that. and it's been that way since nickelodeon has been relevant - most of their animated series have grossout humor on the table 24/7, with things like farting, feet, boogers, all kinds of good stuff - and i think this has evolved into a sort of a secret special interest dealio. the people best at making grossout humor are people who are really invested into that type of stuff right?
also, the difference between slapstick and special interestistic is thin. for like half a century now we've had shows which have inflation and other things just out there