Why do they do it: a penalty, even a free kick outside the penalty area, can be incredibly advantageous. Getting an opposing player a yellow, or red, card is also helpful.

Why is it allowed: the sport has been hesitant to allow too many pauses to check computers, we have definitely seen that happen this world cup so far. But, if a referee catches a player intentionally faking they have and will reprimand them by giving them a yellow, or red, card. Two yellows and they automatically get a red card and their team will be down a player for the rest of the game. That and they usually cant play, at least, the next game.

As we get more technology involved, it may be more difficult to get away with cheating, but then, new methods to cheat may then evolve as well.