FWIW, here's my take on the Salah penalty incident.
1. According to the Laws of the Game, you can't push or pull someone - it's a foul, and it pisses me right off if it's not called when I'm watching and especialy when I'm playing. (the offence comes under: pushes, holds an opponent, or impedes an opponent with contact)
2. At all levels of the game, referees turn a blind eye to a certain amount of pushing and pulling (and it's often referred to by commentators as a player 'using his strength'), especially if the person being pushed/pulled tries to play on or pushes back.
3. In certain situations, a push or a pull (even a small one) can completely put you off (happened to Raz many times, not least by Kyle Walker when he was at Spurs), but if you stay on your feet, you get nothing.
4. The consequence of all the above is that if you're a striker who keeps getting grabbed (even a little bit), you might eventually say "fuck this, let's try going down", at which point the referee may well give a foul. Or not. More likely to if your shirt's red, of course. Then your incentive is to go down every time you feel contact.
So you can either:
a) write it into the Laws of the Game that a push/pull has to be significant to be called, in which case things mostly remain as they are now, it's not a foul, and Salah gets a yellow for his ridiculous dive.
b) any pushing/pulling is called as a foul (as is currently in the Laws of the Game), in which case it was a penalty, Salah wouldn't need to pretend to be shot, and we'd get 4 or 5 penalties every game (of which we'd miss 4 or 5).