So it seems to be that the dungeon has its own consciousness, speaking only through flavor text in the notification windows. Here's my theory: This dungeon was not made to be a death game, but over time its purpose has been twisted. Either by eras passing or the Rabbit manager being added later.
Think like the cube from the movie The Cube. A giant structure filled with danger serving no purpose but to slaughter people put inside it. Unless it had some other original purpose that its still trying to fulfill. Like maybe a training ground for heroes.