In some ways this is a good thing. It is good if bipolar people get the medication they need faster, and can start living their best lives. But as someone who almost died to depression, the "help" out there is criminal. It is not a disease we have a cure for, in fact it's not clear to me it's even a disease in most sufferers, but a healthy and rational response to societal decay. I do not believe some disorders will ever be satisfactorily explained by individual-centric medicine, in the same way history will never be satisfactorily explained by great man theory.
Recently I heard Neil Degrasse Tyson saying that people came up with averages more recently than with calculus. It's not something people find relevant naturally.
Slightly more seriously, things will be on an upward trajectory until they aren’t. There are some decent reasons to think we might be nearing the peak.
Whoa now. That may be true within a strict scope of the "arithmetic mean" definition of "average", however, the idea of average as a 'concept' is much older. As an easy example, early references to agrarian yields (crop farming and how much food they produce) talk about average size of crop harvests, etc. Early tablets from Mesopotamia talk about average yield size, and those are dated 700ish BC.
There is a significant meaning to my claim, which is that it's unconvincing to make exactly the sort of "it has always worked out before" argument that you're making here.