One possible problem is that it is the prime example of pseudo science. It is not falsifiable. But that just seems to be the beginning of the problem. The major problem is their main result is to take normal people and make them mentally sick. That is there seems to be some internal evil that characterizes the whole profession. [They seem to have the ability to inject true mental illness into healthy people and by that to force them to keep coming to them for some imaginary cure.]
The main problem seems to be it is a profession that attracts mentally ill and sadistic personalities.
I think the goal is to define all of humanity as psychologically sick except for psychologists.
The disciple of Israel Salanter Isaac Blazer wrote the best cure for sickness of the soul is Musar bringing that idea from the Rambam in the Rambam' Musar book Eight Chapters. Why Musar? Mainly Musar is about being a mensch a decent human being. It reveals that that is what the Torah is about. This is hard to know and even harder to fulfill. But since the religious world itself is mainly satanic the best approach is to learn on your own or in Reform and Conservative synagogues but avoid the religious world. [Unless you happen to be in the area of an authentic Litvak Yeshiva or a Mizrachi yeshiva.]
If you need confirmation of this view take a look at all the people that count the mitzvot, not just the Rambam and you will see that all there are plenty of the 613 that have to do with good character. So good character is from the Torah itself--not just from the words of the scribes.
In any case the religious world is very evil and very sick and they may hide behind Torah but the essence is wrong.
[Musar mainly refers to Mediaeval books of Ethics like the Obligations of the Heart. There are also books from the disciples of Israel Salanter which are very good.]