[{quoted}](name=Chembaron Yamada,realm=EUW,application-id=3ErqAdtq,discussion-id=VQwzkL6z,comment-id=00020000,timestamp=2019-05-29T18:42:25.907+0000)
Because sometimes a tool is so powerful, that it seems fair to give the enemy an advantage if it is used, too.
Take Kindred's ultimate for example. And considering that Mordekaiser already steals stats during the ultimate, giving him an advantage at winning the fight, I actually don't think it is such a bad idea to reward the enemy if he wins the duel.
Kindred's ultimate, like the Bard example, isn't intended as a DRAWback, it's a mechanic that emphasizes not just skill but a neutral force.
Mordekaiser is not a neutral force.
Also, a skilled kindred can mark a champion, towerdive, and R - They cannot die for a few seconds (but the tower can) so Kindred gets time to cook the Mark on her target before delivering the killing blow with her E execute or just the general damage aa+Q and/or an ally can get. Morde has no reason nor strategic design around "What if I gave 10% of my ms and tank stats to the enemy Vayne?" nor would it make any sense for it to do that.
Soraka's R doesn't effect enemy champions, Camille's allies are not pushed out of Hextech Ultimatum nor barred from entering/leaving it, Ekko's R doesnt rewind the damage dealt to any enemies.