They were banned after a few folks got killed by being hit on the head with them. Scott from Kentucky Ballistics managed to get a set and was, eventually, able to illustrate how dangerous they actually were. Now, I realize that there's probably some folks out there who will shrug off the dangers of them, based on that video. However, I think that this second video will establish, quite clearly, that the things were dangerous. That's right, the fucking Romans used them in war. (In one of his other videos, he fires a load of them from his trebuchet.)
Child-me danced with the Grim Reaper with common objects like tricycles and coffee tables. They weren't gonna fuck around with having lawn darts around.