Something can be causal or even predictable but still strange and difficult to reconcile.
I do think that there is a component of fashion or social currency that has piggybacked on medical awareness, or perhaps as a byproduct of its mixing with moral credentialism of disadvantage.
I'd argue it isn't. The first edition of the DSM was published in 1952 [1]. This is right after "the routine annual comprehensive physical examination (PE) became a fixture in American medical practice" [2].
Add 25 years for a generation to be educated, another 25 for the old guard to retire, and you'd expect the paradigm shift around mental health to land around the millenium. Unless you have evidence we had a nonlinear jump between then and now, I'd argue the trend is analagous to folks becoming aware of and culturally assimilating the concept of blood type.
[1] https://en.wikipedia.org/wiki/Diagnostic_and_Statistical_Man...
[2] https://www.ncbi.nlm.nih.gov/books/NBK82767/