Because people with mental illnesses don't just want to be talked at, over, or around. They want you to hear them out, even if you make decisions that go against their wishes, they'd still like their wishes to at least be acknowledged.
We want you to understand that we are not children. We are adults who are ill.
If you made a decision for a cancer patient without at least listening to their opinion, there would be uproar. Make a decision for a mental health patient without asking their opinion? Meh.
But Filer explains this without ever explaining it. He simply allows the character to tell his story, and places the reader in Matt's shoes for a while.
Not that he paints Matt as an angel - far from it. He's not some martyred saint. He's a real person, with all the flaws and quirks that brings.
He's not pitied, but neither is he demonised. And that is an incredible achievement.
And I love the non-linear structure.
We experience the story as Matt does - with flitting thoughts as he moves from one train of thought to another. We experience his present as well as his past, complete with complaints at people reading over his shoulder.
This is an excellent book guys. Read it.