Everyone just a copy of a human.

Gooseworks mentioned the whole cast cried reading the script. So what. Could cause this? I wouldn't say a death alone would cause this.

But the revelation that there truly is no escape and their human bodies have been doing their own thing. All that's left is to accept the fact this is their new home.

They could turn it off, but remember Pomni found this place in an abandoned building so if it's just turned off they could come back. The only true solution is to erase everything.

Also abstraction? The game is simply making a container for their minds. The mind can change still. But if the mind changes too much for the system to handle they simply abstracts. So it's simply not the solution. Unless that's how they erase everything, by abstracting and overwriting everything.