User blog comment:CaveJohnson333/Sunset Shimmer vs Zone-Tan ~ Cave's Rap Battles April Fool's Day Special/@comment-80.213.49.101-20170518094121/@comment-25579736-20170518094438

Celestia only resorts or prison if Friendship doesn't work. Discord was a tyrant who ruled in chaos for god knows how long, was sealed, came back and did more evil stuff, but she still tried Friendship first, and it worked, so no prison.