People build a lot of cubes and decks and dont necessarily want to break the bank in order to get the cards they want
So, even though it's not destroying anything, you can actually prevent not only the Ba Sing Se that is already on the battlefield from making any relentless 2/2 attackers, but all future copies of Ba Sing Se
Controlling a Ring-bearer can give you quite an advantage, at the cost of that creature likely drawing any removal your opponents can throw at it
InQuests version of purple focused on Shapeshifters and mind control effects as its mechanical identity
Enchanting a creature does involve targeting that creature, which shroud prevents
This tribal deck, built around Knights, brought back the Eminence ability, meaning you don't even need to play your Commander to start generating value from him