It is totally beyond me why anyone would have such distrust of what they hear to rely on DBT.
Apparently so. The explanation is simple: If you understand what scientists have learned about human hearing perception over the course of decades, then you will understand why we shouldn't always trust what we hear, and why in these cases listening blind is far more reliable than listening when you know what you're listening to. I suspect that you don't want to understand this, because it will upset the beliefs you've acquired over the years.
Now, there's nothing wrong with not knowing (or not accepting) this. After all, you don't have to understand the principles behind an internal combustion engine to buy a car. And if you can afford a multi-thousand-dollar audio system, it doesn't really matter. You'll probably get good sound regardless.
But if you can't afford that kind of an audio system, it can matter a lot.