Private mental health providers in the US are pretty unsupervised and have a conflict of interest in that they make more money by keeping their patients/clients unwell, which can lead to negligence and abuse. The only thing keeping in line is the possibility of someone informed and insightful enough to report them to the licensing board or pressing a lawsuit.
For example, if a provider has poor integrity, it is in their best interest to not treat depression, but rather help the patient/client feel good for the moment. What the patient/client experiences is that they feel better when they see their provider, so they become dependent on their provider. This ensures the provider a reliable source of revenue.
Another issue is that masters level therapists, while capable of providing treatment for simple cases such as a clear depressive episode, are not properly trained to conduct thorough assessments for complex cases, meaning they can misdiagnose quite easily. Complex cases would be better treated by a well-trained psychologist that can conduct thorough psychometric assessments that are quite sophisticated and take lots of time to analyze. These services are costly and the vast majority of insurance policies won't cover them.
Relevantly, yet another issue is insurance for mental health. Most insurance policies that pay for mental health services pay low, so the care you receive can be substandard since the more effective providers are charging what they're worth in a market economy. One example that comes to mind is Better Help. They pay providers insultingly low, like around $30/hour, while effective providers are charging ~$150/hr out-of-pocket. That means that when someone uses Better Help to obtain care, they're getting the bottom of the barrel therapist.
Lastly, the majority of family and marriage therapists aren't properly trained in narcissistic emotional abuse. This can mean that therapy would not only be a waste of time, but can make things much worse as they can help the narcissist abuse the victim even further. Narcissistic abuse is quite complicated and requires a relationship therapist that specializes in that to properly assess and help the victim escape.
Tips: If you have been seeing a therapist for 12 sessions, and you haven't realized any considerable long-term changes, find another therapist. Also, if your therapist doesn't call you out on your bullshit, let's you ramble about tangential matters, or focuses on helping you overcome specific weekly struggles, rather than helping you develop skills and restructure deep cognitive matters to address them yourself, find another therapist. An effective therapist would develop a clear treatment plan with you that aims to meet objectively measurable goals within a certain time frame.
Note: I am not a therapist. I have just worked in the mental health field and have friends that are therapists.