Originally Posted by
Lagtime
So, first, of course the Metagame reason starting with 3E, the Planes were made very safe and comfortable, along with everything else in the game. So the "prison" part is mostly in name, as they won't put any negative rules in the book that might make a player sad or unhappy. So the idea that a player might fail a save and be stuck on Carceri would be out of the question.