The term, "chemical imbalance" I think is often used, as mentioned, to give a simplistic answer to the patient. For example, if a patient wants to know why they are depressed, there are multiple answers that can be given but, "chemical imbalance" sums much of it up in two nice words. I've also seen ads for anti-depressants use the same words to explain why the medication works, as it is alleged to restore the chemical balance. The problem with it that I have is that it's a, "masked answer", in that it pretends to highlight the root cause but in reality, it doesn't.

Another problem I have with it is it suggests medications are the only answer. This however is false because psychotherapy alone has been shown to be just as if not more effective than medications alone. At first glance, this shouldn't occur because medications are meant to fix the imbalance, not simply talking. This isn't a universal statement because it only applies to certain mental disorders, such as depression and not to schizophrenia.

In sum, I think they're just buzz-words.