I'm not an ear expert but I that actually makes sense to me. Take a piece of tissue paper for example, you can't hold even a 3 inch strip between your thumb and forefinger and expect it to stand, but a 1/2 inch strip would. However, you'd have little problem with a longer piece of construction paper.
Personally, I'd rather see natural ears over a military crop on a Dobe though... And I would imagine that very thin or weak ear leather is taken into consideration by responsible breeders, since the Dobes ears are such a contributing factor to his overall appearance...