Why do you get a yellow card in game if your caught diving but if you manage to successfully dive and get retrospectively punished you get a two game ban? Doesn’t make sense, surely the ref should get punished.
Not the same punishment because it wasn't spotted in the game so we profited from a penalty and goal, and a subsequent point for the draw.
Now, I know a 'yellow card with no ban and no penalty' doesn't equate to the same as 'a penalty during the game plus a two match ban' - there's no way to set a correct punishment to allow for the fact we profited from the decision, but that's what they are trying to do.
The punishment doesn't fit the crime (because there is simply no punishment that would), but the FA/FIFA/whoever hope that the punishment acts as a deterrent*.
*to stop people like Niasse from running into a defender's arm/shoulder as they try to deliberately block you, I guess...