Considering that



-Discord was sucked dry by Tirek



-was powerless against Chrysalis' throne



-could not break the spell Celestia put on the Elements (in Keep Calm And Flutter On)



-was defeated in ALL alternate timelines safe for one (though I don't take the Season 5 finale seriously)



-got sucked dry AGAIN by Grogar's bell



-was physically banished from friendship school's ground by Starlight Glimmer



-got outsmarted at every opportunity, even by Fluttershy



-never dared to directly and openly confront Celestia (he had all reason to, but NEVER did)



-almost killed himself simply by "not being chaotic"



-was made sick and helpless by a worm's sneeze



I highly doubt that Celestia couldn't do anything without the Elements against him.



The Elements are simply the less violent solution ¯\_(ツ)_/¯



