Many other requirements have been instituted from iOS version to iOS version that require substantial work to bring old code up to current App Store standards. Among them are things like screen size support and retina-resolution assets. Meanwhile, many of these apps still work perfectly fine on iOS 10, even if Apple won't accept those submissions today.

Oh dear, note that while your interpretation makes perfect sense upon re-reading my comment I really meant "developer" as the developing company rather than the actual person, and "dead" as in folded/gone, rather than the actual physical death of a living human being.