Agriculture dates back to at least ~10,000 BC (the "Neolithic revolution"). Effective farming (i.e., not dying of starvation) requires planning for changing weather conditions. If you think Neolithic farmers didn't have a vested interest in detecting patterns in weather cycles, you're sadly mistaken.
Hell, the term "meteorology" was coined by Aristotle... in a book he wrote... called Meteorology... in 350 BC.
Got the daily weather report for Athens for the years 150-100 BC?
Neolithic man had a deeply vested interest in the weather, but that doesn't change his advancement of weather science. The gods were useful for many thousands of years.
Sure, the general idea of watching the weather -- long history there. But that just proves my point. There was a huge gap between seeing and naming it, recording it, spotting patterns, making falsifiable theories, and making predictions. We're just at the "seeing and naming it" stage with climate science. The use of computer models hide this fact, sadly.
Here's a real prediction, with actual confirming evidence: giving someone with a high MADRS score an SSRI will reduce their score.
That's beyond seeing and naming depression, it's beyond recording patients' reactions to SSRIs, it's beyond spotting patterns in their reactions, it's even beyond making falsifiable theories about its mechanism of action. It's making predictions which are confirmed on a statistically significant basis.
Does this mean you think psychiatry has the same epistemological standing as physics?