Modern psychology and the social sciences are a joke. The scholarship allowed is directly at odds with logic.
Also, please don't take threads on generic tangents, which are repetitive and therefore less interesting than the specific topic at hand.
Worse, most of the time I hear people criticize psychology, the person is implicitly using this as an excuse to not critically examine their personal beliefs about how human minds work.
Paychology is hard, and we're feelinng around in tye dark, but chemistry had the same problem 300 years ago with ideas like phlogiston theory.
What may apply in one context does not apply in another context. Fundamental matters such as qualia vs quanta also apply. For example, one person may act differently in the same situation depending on how much energy one has & what mood that person is in.
In chemistry, one can create systems of limited scope (a single chemical reaction). In psychology, it's inherently more difficult to isolate variables (in some contexts it's impossible) due to the complexity of the essence of the domain & the limited information within the model definitions. The more information required of a model, the more expensive it will be to apply.
Another issue is the domain language is always changing. Disorders are recategorized on a yearly basis. Some disorders also act as a catchall for symptoms which may have different causes.
One can also argue that the expectations of others (e.g. the greater society) is "sick" & projects it's sickness onto individuals that do not fit it's criteria of "good" behavior. Despite the numbers, there's going to be unavoidable subjectivity & cultural/individual presuppositions in the sciences.