> Instead of saving the time in UTC along with the time zone, developers can save what the user expects us to save: the wall time. Ie. what the clock on the wall will say.

That's not at all foolproof, although it works for the case the author describes and probably works for most people most of the time. It wouldn't work if, for some reason, I'm entering a calendar event for something I know will happen exactly n hours from now.