I don't think children should be going anywhere near such things without adult supervision, but completely banning sale seems like a wildly disproportionate response.
But throwing a dart high in the air and hitting a wandering 2 year old actually did happen, and there was no real attempt to only their the darts in one direction
I was a nine years old and I tossed it as high and as far as I could. I realized it was coming dangerously close to a friend. Everybody had their backs to me. I yelled, but nobody heard me.
In my memory it landed inches from them, but that could be because I was young and scared shitless. Maybe it landed fifteen feet behind them. All I know is it scared me enough that I have never touched a lawn dart after that.