There are hundreds of therapies. A therapist cannot be competent (or eclectic) in all of them. It is unethical to try to be or to so present oneself.

If a client wants (say) Jungian therapy, and the T is not trained in Jungian therapy, then it is the T's professional responsibility to refer the client to someone who is trained in it.

I agree that this requirement is thought to be in the best interests of the client, and I understand that you object to such requirements. For better or worse, though, therapists' rules of ethics do require a referral.