bent crank ?

Maybe more likely with an old Ford flathead V8 crank with only 3 mains; they are a lot more 'spindly'....perhaps. If thye really did that, I would have had a few dozen bent cranks over the years.... I never heard of storing them on end 'til now.

Storing cranks on end makes sense if you have a lot of them.... it takes up less space... Maybe that's what the old wives really had in mind...."You're not bringing that crankshaft into my kitchen again unless you store it on end...I'm tired of tripping over all your junk!" LOL