A quick review of the FPL diagrams in the wood handbook gives a better explanation, but you have to remember that all shrinkage, like politics, is local. The largest contiguous area is moved away from the largest dimension physically by hollowing. Note that on a platter you can do this on the reverse, under a rim, and get the same stress relief if you have a broad "foot" section to work with.
I've posted a couple/three endgrain pieces here in "gimme" woods like elm and birch, but they were done basically the same way, where the blank looked like a plano-concave or even double concave lens while drying, producing a platter when re-turned. Even posted a weird cherry form with two heart wings. Don't be discouraged. Not only can it be done, though at risk and with care; it can be done to produce things which do look good. At least for my eye end grain can be quite handsome.