Porn does calibrate expectations, especially for boys (and girls) who aren’t getting a lot of other real, frank, sexual education. Teaching that things that can be very uncomfortable or downright painful as a part of vanilla sex is a huge disservice to all, but particularly to girls. I agree that there’s room for whatever kind of kink you are consensually into, including the kind that causes pain, but you are exactly right that it needs to be made clear that it’s kink.