Why is a spray like ethyl chloride that evaporates quickly used to numb a sports injury during a game?

So the player can continue to play even with a serious injury, & exacerbate that injury so he is no longer able to play afterward for a sustained period of time. In other Words, it is very temporary & usually has very poor after-effects on the player. Should not be allowed.

If the sports team owners thought they could get away with pulling out a needle & jabbing it into a player during the game, they would. But there would probably be a huge stink. So instead they spray the painkiller on the skin instead of injecting it.. Usually. Sometime they take them back into the locker room where prying eyes cannot see the dirty work.. & fire them up. Bad stupid.