Help me understand this Minor Illusion "Inviisibility" trick!

[Cybren]

Lol, I'm guessing this has been hashed out before? If so, sorry to make a new thread. I'm just not seeing the justification for making working mirrors.

Im skeptical of allowing a player to make a perfectly working mirror as well, but there are some that insist that not being able to make a mirror would make the spell useless.