People also just speak differently. You're allowed to curse on the internet, and as someone who lives in Queens, I honestly have trouble speaking without cursing. It feels kind of stilted and overly proper. Language is fluid and evolves.
But presumably you don't write in every "um", <cough>, stutter and mis-speak so why keep in the swear words rather than cutting them and increasing your readability and information density? You may have trouble speaking without cursing but you clearly manage to write without including the curse words.
