Written by Alan Flesch (aflech@calvin.usc.edu).
Jyhad is a game where Methuselahs use minions to try to destroy their rivals.
Master Cards represent the actions of the Methuselahs to give their minions advantages. These are largely strategic items rather than tactical. There is little interaction between Methuselahs Sudden Reversal is one of the few Methuselah/Methuselah interactions in the game. Very little a Master Card can do will affect another Methuselah (it is the violation of this principle which makes Fame such a lethal card).
Minion Cards represent actions between minions. The game is largely played on this level, with minions acting to carry out the whims of their masters. The game consists of the acting player trying to act, and the minions trying to counter those actions with reactions of their own (stealth/intercept, political actions/voting blocs, etc).
Direct Intervention has the Methuselah interacting in the Minion level. There is no interaction between minions. There is no gameplay. There is only the great NO.
It violates the division between minion/Methuselah. It violates the gameplay scenario. It violates the inscrutability of the Methuselahs (especially since multiple DI's can be played serially). It violates the idea of the game.
The presence of DI is seen as the ultimate justification of Overpowered cards. Remove the 'Just use Direct Intervention' argument, and suddenly the discussions on countermeasures become increasingly convoluted and of questionable use. There is no card that cannot be justified by the existence of DI (a card which was created to counter overpowered cards in the first place).