I'd say therapy is more susceptible to abuse (subtle and not) than any other relationship. It is an abuse-generator.

As for disempowerment, I think it's mostly the combination of client desperation and therapist seduction. The therapist is dishing out the most addictive stuff -- attunement, understanding, focused listening, the appearance of caring, and the promise of liberation from suffering. Never mind that it might all be bullsh*t, if it feels real at some level.

Also, therapy is constructed by and for therapists. It is their game. It's a closed system to which the client must conform in order to "get help". There is little wiggle room for the client to assert autonomy or power. That would kill the game. The client gains autonomy and power only when and if the therapist grants it. This is why the client who terminates against the wishes of the therapist creates such a s**t-storm. And the therapist will try to manipulate the situation to either get the client to continue, or to make it look like they (the therapist) made the final decision.