Easily Offended

Why are some individuals so easily offended by daddy kinks or girls calling their boyfriend "daddy"? I saw something on Facebook saying how it's disgusting and seems like a father/daughter relationship and how girls should never call their boyfriend daddy, and that it's disrespectful to their real father. Why do some people have such an issue with this?? And others saying BDSM is evil and not right, that it's sick and twisted.