It's actually a challenging job being a therapist. They need to have patience and sit and listen to the patient because the ultimate goal is to help the patient help themselves. Also to help the patient understand themselves so they can begin changing things about themselves that can improve their perspective as well as helping them develop skills to not only better manage themselves, but others as well.

Learning about all the different challenges/labels is only one part, the next is seeing if these labels apply to the patient, then listening to that patient and helping that patient not only better understand their challenge but to better manage whatever is happening in their environment that is causing problems, some of which they may be unknowingly creating themselves.

Also, a therapist can encounter a patient that has a challenge the therapist doesn't feel comfortable treating and sometimes they refer to a different therapist or gently tell the patient they can't help them.

For example, not all therapists are experienced in treating trauma ptsd patients, that's pretty specialized. Or trying to treat a patient that dissassociates a lot because treatment does require discussion.