Parts of site failed to load... If you are using an ad blocker addon, you should to disable it (it blocks more than ads and causes parts of the site to not work).
"Sometimes the seed hull and the inside skin is still attached to or enclosing the leaves. This happens if the seed was not planted deeply enough. Usually the seed hull is detached as the seedling emerges through the substrate." Germination Troubleshooting Guide
It makes sense to me, that the friction between the seed and the dirt while growing upwards would have some effect on detaching it from the cotelydons...
Then again, Rusty makes a good point... Hey shit happens, nothing you could to about it.
Sorry...but I respectfully disagree with the website claims. The hard outer seed cover isn't attached to the inner seed cover, (or it would always come-off with the hard cover) so friction on the outside shell has nothing to do with the inner workings. Only way I can envision it making a difference is in the length of maturity (in days) that the seed is underground. But that's not a friction thing, it's a size/maturity thing.