I think there's a difference between police-ing speech, and clarifying it. Language is hard, and misunderstandings are surprisingly common, and many world's evils comes from pure misunderstanding.

Most misunderstandings arise from people having different understanding of same words - so approaching agreement on the meaning of words is important to reduce misunderstandings. The problem is the language is self-manifesting - the word gains the meaning from the way people use it, even when the meaning differs from the original (perhaps academic or technical) meaning.

So one side has to stand back - either academia (in this case, psychiatry), or the general population. Since academia largely relies on solid, defined meanings of words, while the general population relies on "how other people are currently using it", it's supposed to be easier to change the usage by the general population. Although it's pretty hard to do both ways.

Otherwise, we end up with words having two distinct meanings, one professional, and other layman.