While I understand where you might be coming from, I think you fundamentally misunderstand OP's point, while lacking awareness of what it can be like to be a patient in the psychiatric system.
You acknowledge yourself that if you have a bad doctor, you need to change to a better one. But you also say to always trust your doctor, or you won't get better. These two statements can't coexist, because if you trust your doctor no matter what, you won't be able to protect yourself from bad doctors "and change to a new one" or whatever else protecting yourself might entail.
Now, OP isn't actually saying not to trust a doctor that you have found to be good and helpful and trustworthy. What OP is saying, is that placing blind trust in a bad psychiatrist can lead to real life harm for psychiatric patients.
Psychiatrists have systemic power over their patients, and they can both force you into treatments, and deny you treatments, based on the information you share with them. I'll give a couple examples.
1) A friend of mine who had been struggling severely and unable to work for the past year due to stress and increasing panic attacks/flashbacks finally went to see a psychiatrist at a hospital. The first person she talked to was really nice. She asked about drugs and my friend admitted that she occasionally smokes weed to calm down from the very symptoms that she's seeking help for. The psych was understanding. A couple interviews later she gets a new doctor who has a different opinion. And skip to two years later where the system is still denying her care bc "she has a drug addiction" while the drug addiction clinic is denying her care bc "that doesn't count as a drug addiction" and "she would stop smoking weed if someone cared for her glaring mental problems". She is not alone, this is a very common scenario across the world. If you admit to ever touching drugs you may very well be denied care indefinitely. The community recommendation in my country is to never admit to any substance use, even to people in the system who seem understanding, because others in the system may be less so, and you may never get the care you need. As you can imagine, this gets very complicated for people where the drug use is also a large issue on its own.
2) Another friend of mine went to get assessed for adhd. They said they couldn't finish the assessment bc she was too disorganized, and she was sent to be assessed for a schizo spec disorder instead. She was desparate to get any diagnosis at all bc she really really needed help. Here she was given a schizotypal diagnosis. After this she was being treated for this with antipsychotics. They didn't do anything good for her, in fact they made her worse. She tried to ask to be reassessed for ADHD but was denied bc it was seen as a delusion. Her gender identity (which she had been out and in treatment for, for years) was seen as a delusion, and the psychiatric system blocked her from getting the necessary paperwork to get surgery. Eventually she went private sector and found a good psychiatrist who diagnosed her with ADHD. With adhd meds things started improving, she also got her letter from the private psych and got her surgery. (And she's doing so much better!!) But if she hadn't had the means to go private, then her psychiatrists would've been able to block her from the right treatment and life saving surgery indefinitely. This is an example of what can happen from being honest about even quasi-psychotic symptoms, and the ways psychiatrists often have power to block and gatekeep certain treatments from you based on how THEY perceive you and your reality.
3) A third friend of mine is schizophrenic and on a treatment order. She hasn't done anything criminal, but where she lives you can be put on a treatment order simply if a panel of psychiatrists decide that if you don't get forced treatment, you might deterioate. So for a long time she had injections of a medication that was not helping, but that was causing severe side effects, forced on her. This is one of many examples of psychiatrists wielding systemic power over their patients.
Many psychiatric patients fear being honest with their care providers, because it can lead to forced hospitalization, forced medication, or it can lead to denial of care and treatment. This is not an ungrounded fear. These are things that happen to people. Sure, some may fear this beyond what's realistic in their situation, so anxiety can mix with this, but it is a real thing to be aware of.
And as I've attempted to illustrate with these examples, it's not as simple as "if you get a bad doctor, get a new one". This is often not an option, there's often a paper trail that follows you from doctor to doctor, and even the first doctor you meet have power over you, and can potentially make your situation worse if they are bad at their job.
I know several people who have been severely overmedicated and wrongfully medicated. One person I knew was taking 10 different medications at once, including heavy duty antipsychotics despite not having experienced or being diagnosed with psychosis, and benzodiazepines on a completely irresponsible regiment that got her severely physically addicted. She didn't start to get better, before she slowly weaned off all these substances against her doctor's recommendation.
In an ideal world we could always trust our doctors, and be honest from the get-go, with the assumption that they know what they're doing and won't force or deny care.
But in the reality we live in, doctors have systemic power over patients, and not all doctors are good. So therefore it is in fact important to advocate for yourself, seek out information independent from your own doctor, talk to others in the community about their experiences, and yes. To be tactical about what you do and do not share with your psychiatrist. And when it does fuck up, you may very well need a lawyer. For example if you want to sue for wrongful treatment, overuse of coercion, or to get you off a treatment order that's destroying your life.
I really recommend doing some research into the kind of abuse and neglect that unfortunately takes place in the psychiatric system, before speaking so confidently on the matter.
Psychiatry differs fundamentally from oncology in its views on patients' rights to autonomy, and in the level of power granted to your doctor to control your life. But that said, most of us are not experts on oncology either. Which means that in reality it can be pretty hard to know whether your oncologist is good, and whether you need a new one. And somatic medicine is not free of bias, abuse and neglect either.
So TLDR, OP isn't saying not to seek help or not to trust your doctor with anything, she's saying to be aware of the potential pitfalls and to be tactical in your approach and to advocate for yourself, and not to trust psychiatric authority blindly.
That's not ableism, that's realism.
