My guess is in cases like this it comes from collective real-world past experiences (in either AI or biomedical research or both) of what's going on behind the

My guess is in cases like this it comes from collective real-world past experiences (in either AI or biomedical research or both) of what's going on behind the scenes, leading to skepticism about claims. For what it's worth it doesn't seem depressing to me, it's more like holding it up to a standard that guarantees real-world utility. It's also depressing to see misleading claims being used to further academic careers at the expense of patients and investors. I think you're right to question whether skepticism goes too far, but I don't necessarily see skepticism as a negative thing. If it holds up to places like HN skeptic corners it probably will hold up everywhere.