IMHO, the martial arts are not a substitute for psychotherapy. It may be a good adjunct, not never a substitution.
Conversely, psychotherapy is not a good substitute for training.
And, to address Janet's assertion above, I concur, a dojo is definitely not a therapeutic milieu. It is training for whatever good it brings to whatever person is training through the pure structure of aikido. Not Therapy, yet sometimes therapeutic. If you get my drift.