Just to be fair, even the pin type can fail. They are made of much lighter material, and if someone doesn't put the pin in all the way (user error, just like not latching the levers all the way) then the stress is not applied evenly across both sets of holes.

I had a friend who did just that - he couldn't get the pin all the way through so he thought it was good enough with just one side. It wasn't, and the jackstand ripped open at the hole letting the load drop. (Lucky for him, he was putting the jack under the other side of the car at the time so there was only his ego hurt.)

My point is, anything can be used wrong. If used correctly, I'd agree that the lever type is much stronger.