I love philosophy! I'm so glad you started this thread. One of my favorite books is Irving Yalom's, Existential Psychotherapy. Have you ever read it?
I think there have been times when following a faulty philosophical train of thought of mine, has led me to a depressing dead end. Then it's been tremendously helpful to find out what directions other philosophers have taken. I think it serves the same purpose and it has the same feeling as when a therapist helps me become aware of other options or possibilities. (I really got a lot our of reading about Voltaire's approach to life.)
I had a psychiatrist once who did seem to understand how my thoughts could color my worldview. His reply to my struggles with the questions of "isn't it really all meaningless" and "is it really worth it all" was, "Yes, that is the big question. Isn't it?". As if he had struggled with the same question. But it would have helped me so much if he had been able to suggest that I might want to read what Kierkegaard said about passion and a leap of faith or what other philosopher's have come up with.
So, not only do I believe philosophy would be helpful therapy, I think that for some of us, like myself, who spend way, way too much time thinking and worrying about the big questions, an awareness of the different schools of philosophy could be essential to our emotional health.
I think I once read about some association of philosophers who worked counseling people. I need to look that up again. I look forward to hearing thoughts you and others have about this topic. Thanks, so much, - Swim