IMO the answer will vary as widely as the modern/recent definition of overlanding itself.
I'll say that in many (most/all?) of my global vehicle travels (Expeditions7 & ExpeditionOverland), a rear locker minimum has not only been useful but arguably mandatory. I can think of a variety of scenarios where a winch simply wouldn't have been a suitable replacement for at minimum the rear locker. I'd argue that ATRAC or similar is a decent substitute worthy of discussion and likely suitable for most common "overland" routes.
I'll say that in many (most/all?) of my global vehicle travels (Expeditions7 & ExpeditionOverland), a rear locker minimum has not only been useful but arguably mandatory. I can think of a variety of scenarios where a winch simply wouldn't have been a suitable replacement for at minimum the rear locker. I'd argue that ATRAC or similar is a decent substitute worthy of discussion and likely suitable for most common "overland" routes.