My theory is that focused, long-term mechanical pressure from within, is the culprit.
I suspect that, barring any violent abuse while inserting a disc into a slim drive, the pressure is not narrow / strong / long enough to cause this type of stress on the hub.
I have, however, noticed this damage on CD’s (and DVD’s) in storage when using a specific type of jewel or library case. I have chalked it up to poor design of the hub retaining mechanism (e.g. 3-point contact instead of multiple places as in the original design jewel case). All of those cases are now in the garbage, the discs recopied and placed into less stressful storage cases.