i don't think this is entirely true. It can be but in a general sense it's not always directed at a person but sometimes at objects, or life's events. One can be sarcastic in their remark underscoring the ridiculousness of something. Say a news story you found rather off and even stupid. You might joke with a friend "yeah that story was soooooo right on" dripping with sarcasm who's gotten hurt? no one. The friend usually will understand your sarcasm and unless it's at them it's not necessarily as horrible as you frame it.

Take this to the extreme where you're even sarcastic with a friend and at them. If you know this friend, like I do one of mine on facebook, we have entire chat threads full of sarcasm throwing back and forth. no one gets hurt, it's how we, as two males, kid back and forth. Like talking about how a girl thinks I'm cute and he might say "yes, [name redacted] you are SO HAWT" not hurting me, it's funny.

*and after my reply I just realized you did add "often times" so I apologize tht I misread your post as if it were saying it's always.

It can hurt but as with anything words, joking and communication can be misused but that's a different subject entirely.