I'm pretty sure the dead ends are there to emphasize that this is a game. Ren breaks the fourth wall when we reach the "bad" endings by directly speaking to the player. Choices leading to a dead end shouldn't even be there and are probaly a result of Ren messing with the game's narrative. (At least that's my theory, Sai said she doesn't want to reveal much about the purpose of dead ends)
Another possible reason is simply that the game is still a WIP demo, and the route's leading to dead end's will be added in the future