"You have to be willing to help yourself" is perilously close to "psychotherapy only works on people who are capable of changing of their own volition", which calls into question the entire purpose of psychotherapy. If I could change my way of thinking through sheer force of will, why would I pay a professional $100 an hour to sit and listen while I do it? It evokes the classic defence of the quack - the spoon only bends if you truly believe in the power of the mind.
If that problem is framed as "some patients are too sick to treat", then at least it shifts the burden of responsibility onto the therapist; it's not the patient's fault that the psychotherapist lacks the neccesary tools to facilitate change. Blaming the patient for having a bad attitude just makes the profession of psychotherapy look ineffectual.
When I went in I had some major anxiety problems, and by working with my therapist I was able to identify where those problems came from. I started taking steps to change how I lived so I wasn't as anxious anymore.
What sort of magic are you expecting from psychotherapy? You're paying someone to help you solve your problems. You're not paying someone to solve your problems for you.
On the other hand, going to therapy is forcing yourself to do something that is difficult, sometimes painful and requires a lot of effort and resources (both time and money). I don't see the relationship between voluntarily going to therapy and advertising inducing you to buy things.
A real intervention doesn’t require someone to help themselves; an appendectomy doesn’t require patient participation and motivation.
Okay, this is clearly not what we were talking about. Sorry I was not more specific in my statement to generalize to all scenarios, ever.
Edit: I think it is also a pretty fair assumption that if someone is shot or their appendix is about to burst, they would want help. The key difference here is that someone who is shot is not capable of helping themselves - with regards to many things people go to therapy for, the only way to fix your problems is going to be taking some actions yourself.