But this begs the same question: if mental illness really is what psychologists say it is, and if treatment is a learnable skill, then the practitioner shouldn't matter that much assuming his training was good.

But most evidence suggests that some "je ne sais quoi" has to exist in the therapeutic relationship.

In other words, Freud was right about Transference as a necessary ingredient to psychotherapy (and probably about a lot else that is still too controversial to talk about or pass IRB muster).

Isn't the "je ne sais quoi" just feeling safe to be themselves and open? Whatever that means for each person

Well, sure, but "people in their life that they talk to" aren't really therapists. They're functioning quite differently - they can have a personal involvement that a therapist, ethically, isn't permitted to have. The sorts of things someone talks to with their friends overlaps with but is also often quite distinct from the sort of thing a therapist is probing for. There's no direct financial incentive to keep the "patient" coming. And they're making no claim to, broadly, help someone improve their overall mental health - people vent to their friends because it feels nice, not because it's necessarily constructive.

I promise you no therapist who is not engaging in illegal behavior cares about you coming back. This is pure delusion.

So the patient is holding the therapist wrong?

Although I agree it's a matter of finding the right therapist, I think that undersells the problem a fair bit.

There are large barriers to trialing a lot of therapists, and finding the right one can be like finding a needle in a haystack. Therapy is quite expensive, and many therapists already have a full caseload. And the pool of therapists is very homogeneous: essentially, a ton of well-off white women who might not have the tools or shared experiences to facilitate a helpful therapeutic alliance with individuals coming from a broader background than they're comfortable with.

In my experience, most staunch opponents of mental health talk therapy are people who have serious issues and really do not want them to be talked about and fixed. Issues like bad anger management when they want to keep the anger out of anger, eating disorder which makes you not want to heal, because you might get cured and fat.

There is such a thing as being unhappy about actual therapy that did nothing or harmed you. But you see the staunch opponents who never been at therapy and have only movie understanding of it having tons of strong opinions or fear.

"Just one more therapist bro" is what defenders of modern psychology use. It is always your fault the therapist didn't work out. Always your fault you aren't trying hard enough. There can never be systemic issues.