Explain how an entire round of Ski Jump can be canceled?

So the Olympics, which take place every 4 years had an entire round for an outdoor medal event canceled because of…. Snow?

One, can they not just do the event another time?

Two, how is this fair to athletes in places like 4th?

Three, how can mitigation/contingency plans not be in place for the astronomically shocking event of snow at the Winter Olympics?