This is a HUGE concept. Most therapists understand it but tiptoe around it with paranoid delusional personalities (like those in sz) because of their reactivity to such a concept, believing as they often do that bringing it up to them is somehow an attack upon them.
“I am not responsible for my disease, but I am responsible for my recovery” (a phrase I learned in Narcotics Anonymous) was crucial for me to keep in mind… because of what I did to try to “manage” my illness (that wasn’t functional at all).