I do know that NFP types might perceive the sarcasm, but INFP's who I know IRL in particular seem more apt to respond to the comment in a serious/solemn way rather than just laughing at it. So it might seem like they do not get it. But it doesn't mean they do not. It usually just comes off as wanting to ensure no one's feelings get hurt, so they take the "safest" approach rather than the one that might seem dismissive.
I'll be stoic in the face sarcasm when it's fatiguing to me. I am not really afraid of hurting anyone's feelings and I usually know what's going on but I just don't feel and/or can't like expend the energy on dealing with it at the moment. My mind often just won't switch gears out of sincere mode to sarcasm mode. It's not really about fear or anything else but being deep into Fi at that moment at time and not really well oilled up on Ne.
As I said, previously, I can swtich gears on intellectual based irony faster than F based sarcasm.