The last T I saw told me in our first session that he had suffered from Social Anxiety. The fact that I could see him functioning and having achieved a role as a clinical psychologist was a huge boost right from the start.

I'd not like to live in a world where people who'd suffered or were suffering from MH issues were refused the option to help others in the same boat. They should be assessed for their suitability to practice using the same standards as everyone else.

And as others have said, Marsha Linehan is a prime example. She has developed a BPD therapy based around her own experience with the condition in a way a non sufferer probably couldn't have.

Thankfully the days of the healthy "expert" telling the sick "patient" to get well are over and therapy is often a two way process. The therapist can learn as much from the client as the other way round.