A therapist is the keeper of secrets. Neither therapist nor client is likely to advertise what is going on during sessions. You might have pinned down therapists as doctors of psychology who try to help the weak and crazy among us.
Well, the truth is contrary: it is a humble and courageous gesture to seek the help of a professional, not only in moments of crisis, trying to deal with harmful mental patterns or toxic core beliefs, which cause suffering to the patient and his/her or her environment alike, but also on a preventive basis.
So, just as much as it is the job of therapists to diagnose mental health problems and propose and conduct treatments, it is also their responsibility to make sure a diagnosis will never be necessary.