I think unjustified "monolithic thinking" in this instance was bad. I'd say that's because in medicine, so many maladies are multifactorial and thus one shouldn't declare victory till your model shows strong effectiveness in the field.

But "monolithic thinking" is also accepting established theory. Unlimited diversity can open the door to all sorts of crap - I don't want "diversity" in whether a doctor accepts the germ theory of (some) disease, the existence of viruses, etc.