You don't understand.
They want to blacklist all that they do not apply themselves, but then allow a whitelist of select debuffs that other players apply. Other games have this, usually through UI addons.
For example, his Ninja.
Blacklist all debuffs not applied by himself, whitelist for Trick Attack applied by other ninjas, whitelist for Storms' Path. Blocks all other Warrior debuffs, and all dots by everyone else.