Its almost never a discussion of the actual medical necessity or the decision making process of it.

It's saying the right words for them check their boxes. It's mostly a mere formality that they'll be approved. They're just trying to make it as difficult as possible to start with so that you say, screw it, it's not worth it to even fight (which I sometimes do).

But the insurance companies actually don't like the paper trial of repeated denials and the liability of it (from what I understand).