The engine also started as an engine for MMOs, which allowed them rich scripting for every NPC, as well as an inventory for every NPC.
The world fidelity that Bethesda builds, on a technical and simulation level, is unmatched — yeah, something like The Witcher 3 might look better, but it also doesn’t let you interact with basically every item in the world or pickpocket every NPC’s weapon as a way to neutralize them in combat.