People with anxiety and social phobia often feel intimidated by those in positions of authority. So a therapist who may come across as being the one who knows more than we do and without the usual human flaws or experiences could hinder the clients progress and increase the feelings of powerlessness.
I went to a therapist for a couple of weeks, and made a lot of progress just being able to talk and she related a couple of situations of her own that were in her life parallel to mine. This ultimately assisted me in feeling greater ease with her and to not hold her on a pedestal as an all knowing, all perfected human being, guru of psychology but as someone who had a compassionate desire to help others and also had valuable tools to help me in empowering myself, plus someone who'd walked some of her talk.
Think about this in relation to everyday life ....... isn't it easier to feel comfortable with someone who shares their pain with you rather than someone who just continuously listens and gives you advice and never shows you a hint of their own fear or moments of self doubt.