Originally Posted by
Mechalich
It's mostly a late game thing, admittedly. Once you hit a level ~75 or so, quest XP just kind of stops making any difference. At that point only the XP from high-level enemies moves the needle anymore, and since level-equivalent enemies are only found in a small number of high-level areas, it encourages repeatedly hitting those areas. FO76 has a similar problem, where the most efficient way to spend your time is murdering your way through the ghouls at the Whitespring over and over and over.