It’s more surprising that lawn darts weren’t banned until 1988 in the US, instead of the day after they first went on sale. And if you need a good reminder as to why you can no longer easily buy a set, Joerg Sprave built a lawn dart slingshot cannon that explains why.
YouTube is filled with videos of people getting hurt playing with regular darts, and it’s surely not a recent phenomenon. So why anyone thought that making darts larger and heavier would be a good idea will forever remain a mystery.