I'll give you a soccer referee's perspective.
The act(s) of faking an injury, embellishing opponent contact and outright simulation are not actually fouls but are regarded as misconducts in the Laws of the Game. Referees are to sanction those with a caution by showing the yellow card.
Neymar's cynical act of simulation, where he attempted to draw a penalty in the Costa Rica match, mandated a caution (yellow card). Failing to issue that caution was clearly a serious mistake by the referee. Had he sanctioned Neymar in that fashion, it is likely that his subsequent throwing of a tantrum by slamming the ball to the turf a few minutes later in an act of dissent would not have taken place. Neymar could not risk a 2nd caution in that match that would have resulted in him being sent off and suspended for Brazil's next scheduled contest. The referee's failure to appropriately punish Neymar for the dive allowed Neymar two separate opportunities to bring the game into disrepute.
Players simulating fouls and injuries for the express purpose of attempting to deceive match officials threatens to undermine the game. It ruins an otherwise beautiful game by introducing suspicion of nearly every player challenge during competition. Making matters worse, even players at the amateur levels of soccer who see professionals committing these acts attempt to emulate these themselves. VAR is a valuable tool to help minimize players attempts at simulation, however, at the end of the day, it is the players who need to clean this up by holding themselves and each other accountable. If they don't, the cynical acts of simulation on their parts will ultimately ruin the sport.