This reasoning can be used to justify almost any form of "what you don't know won't hurt you". For instance, a world where people cheated on their spouse but it was never discovered would function, from the point of view of everyone, as well as or better than the similar world where they remained faithful.

Most of us think the former world is bad and, if pressed, would explain it by saying that blissful ignorance is not a good thing. Even though "my spouse cheats on me but I don't know it" and "my spouse doesn't cheat on me" are indistinguishable, I have been harmed in the former situation.