Why would you call a therapist an impartial, trained professional? They’re no more impartial than a priest or imam and their provisional training has no bearing on the effectiveness of their treatment. By far the most important predictor of a positive impact of sending a therapist is the feeling that you and they have similar values and are working together[1]. Much as with teachers training has no detectable impact on effectiveness while experience does[2]. A priest who vines with you is as good as counselling as a therapist. It’s the vibes that matter, not the trappings of professionalism.
Psychologists are just humans, it’s true, and so they can be just as fallible as anyone. A good priest may also be helpful but for the non-religious they won’t have the essential shared values. By impartial I mean that they are at a remove from your day to day life, and are at least trained in how to ethically counsel someone.
[1] https://en.m.wikipedia.org/wiki/Therapeutic_alliance#:~:text....
https://www.researchgate.net/profile/Paul-Crits-Christoph/pu...
[2] https://psycnet.apa.org/record/1971-10064-001