Please note I said nothing at all about which option was more useful (if at all), or when an option is useful (if at all). All I said was the programmer can do whatever they wish (including stupid things:-). My statement that both are possible is accurate. The programmer can choose to have their media queries test either the physical screen size or the logical window size. If there's any implication, it's simply that silly website behavior wrt. media queries is the fault not of the spec but rather of the programmer.