When therapists talk about defensiveness, we're talking about people who perceive a psychological attack and there actually wasn't one there. Defensiveness doesn't refer to people who are standing up for themselves in the face of disrespect. This is an important distinction because, when we tell people "hush hush, you're being defensive" and they are merely trying to advocate for themselves, we are invalidating their emotions and discouraging them from speaking up in the future.
I go in-depth into invalidation and its alternative, validation, in The Connection Course: psychologywithdrana.learnworlds.com/course/the-con…