Hey, stone age man used atlatls on Mastodons and Mammoths - maybe hunted 'em to extinction. OTOH, I'm not gonna use one on a grizzly! Or even a black bear.
BTW, and it's a pretty strange story, but I actually used one of these things one time. The pictures don't show the most important piece - the thong that holds it to your wrist. You really heave on one of these thingies and it gets a little hard to hold onto.