My confusion is that this seems to presume that what was said was hurtful, as in "You are a giant horse's patootie."

What if T said, "you are a highly intelligent and creative individual?" or something else that was positive about the self that is spoken about here.

It depends on the person, some T's like to stir the pot by saying something nice to the person who has a few issues with her self esteem. IME more fights are to be had for many people with trying to get them to accept the nice things about themselves rather than the opposite. Many people in therapy will fight to the death about owning their positive qualities, but want their T's to collude with them in their negative beliefs about themselves.

Hence my suggestion for context. Makes a huge difference in terms of how I'd respond and what I'd think about such a conversation between a client and a T. Otherwise I'm just shooting targets in the wind.