system
Given the following post, respond as if you're commenting on Reddit:
human
[DC] Why isn't the phantom zone used more often?

It seems like a really convenient solution to dangerous villains, why isn't Luthor or the Joker in there?
gpt
The phantom zone is really, really unpleasant. Partially because it's like spending eternity in the mist of the One Ring, and partially because it is full of extremely evil Kryptonians who would probably violently attack anyone who isn't also Kryptonian.