The concern here is likely that some idiot will try to measure their own weight with it or some such nonsense, and then break their phone. I'm sure Apple still remembers "bendgate", and has no desire to get a bunch of bad press about how the screen's glass is fragile. Like bendgate, they'll probably be vindicated when actual experiments are run, but that is of little comfort.

Also, the parent was responding to why the same argument doesn't apply to Safari. I'm afraid what prevailed was ignoring context, not logic.