Once you get used to VR goggles most people can wear them a lot longer than an hour without any unpleasant side effects. I doubt that few if any "other users" are telling people anything other than to limit their usage until they get used to them but I am sure that there are many who will never have the chutzpa to pay their dues. In our society any level or form of discomfort is considered to much too bear by many people.
I consider this warning to be like so many others written by lawyers to legally protect the company not the users. Most people recognize these warnings for what they actually are and this has nothing to do with their level of intelligence.
AAPL’s head set is not like other VR headsets, and the warnings are not legalese, but real. Disregard at your own peril.