Imagine if FIFA made this rule:
When a player displays severe pain, they are automatically out of the game. It wouldn't be like a red card, they would simply be sidelined, subbed for, and treated as though they had a real injury. (This still wouldn't discourage late-game flopping, so maybe players who flop near game's end must sit out half the next game.)
*Voila!* No more theatrical bullshit.