I have put this story on here before. And it really wasn't the lynch pin but the result would be the same.
About twenty years ago my then 70-something mother called me and in a panicked voice told me to come to her house right now. I figured she had shot somebody or something and broke all speed limits getting there. To make a long story short the lynch pin hadn't come off, but the nut holding the bolt on the left 3-pt had come off. The result was the same as the lynch pin being lost. She had reached the end of the field and turned sharply holding the left brake and the mower had caught on the left tire. By the time she got the tractor stopped the mower was resting against the left time and the blade had cut thru the tire three times. When I got on the tractor, and a 4600 Ford is tall for it's hp, I could reach out my arm and grab the blade while facing forward on the tractor. Had to pull the mower off the tractor with my truck, have a guy come out and replace the tire, and straighten the lower arms using a torch.
When mowing I check my pins every time I get off my tractor.
RSKY