Right, I wrote the above comment in a way that implied I blame the experts; I didn't actually mean that, by first approximation my "most likely" belief is simply that experts don't help at all.

But it's not hard to come up with actual causal reasons why experts are actively making things worse:

1. if people have confidence in experts, they'll seek treatment from them, and forego other, potentially more effective, treatments (in this particular case: making and talking to friends, not therapists; prioritizing family, not shunning them; prioritizing community, not isolating; etc.)

2. experts make a living selling advice to patients, so it's in their implicit interest to keep having patients (either individually, not curing them, or society-wise, making more patients) (there's a lot of anecdata about "I asked a therapist how many patients they actually cured, and they looked at me bewildered")

3. I've seen some opinions, which echo mine, that experts seeking, reaffirming, and reminding patients of their "traumatic experiences" might hurt more than it helps (e.g. talking to therapist every week makes you re-live your traumatic experience; narrowing the definition of "consent" and convincing women they've been raped; convincing children they're trans (they used to be called "tomboys!"); in general marking fairly normal life experiences - job loss, job stress, death in family, etc. - as "traumatic" and "requiring therapy")

probably more

But if, after the mass introduction of that medicine, the number of people with the disease skyrocketed, then there’s a decent likelihood the causality does actually go that direction.

With other treatments for diseases we always expect the incidence rate to decline — because the treatment works. If it stayed static or went up slightly, then the treatment doesn’t work (and you’re might have slightly higher rates due to new interest in the diagnosis). But huge increases…that’d not be good.

maybe it's difficult to call either way