That article literally just went over how they make good use of the space they put in their games,
this one explains how they connect the themes of narrative with the gameplay design. (plus how many open world cities even begin to reach the population density of AC games?). Not to mention they've created games with better gameplay than GTA and TES,
which both control like molasses compared to WD and FC. They're jack of all trade type games. You can provide open space for infiltration without having a shit ton of uninteresting negative space. Especially when that conflicts with the narrative, such as MGSV's constant harping on the conflict with the rebels, there isn't a single rebel npc that isn't tied up, let alone a group of rebels that dynamically get into conflict with the opposing faction. Nw don't get me wrong, they don't 100% always nail narrative theming and perfect use of space, but when they do, they nail it. The best instance of level design in MGSV is GZ. Kojima shines with tightly controlled spaces and instances of emergent gameplay, but hasn't shown that he's proficient in open world game design and good use of space.